95 Disc w/ persistent O2 & TPS codes, and idle stalling

[alj]

Hi! Greetings.
This is a rather large post w/ 3 problems, for those that may want to skip.

Context: I am a learning analyst, with growing skills and with now some extra time (recently unemployed, but w/ less money these days btw) to work on this wonderful vehicle - love it! - Jeep convert - The goal is off-road use for fun & eventually work - My experience is both reading and working on the discovery for the last year, off and on

I'm looking for hints please on a 95 Discovery with a persistent 44 O2 sensor (possibly 45 as well) that keeps re-appearing after clearing codes.

Symptoms:
1) only occasional, however at cold running sluggish, and improves over time to either stellar (if I've recently cleared codes) or fairly good..., this improvement is mainly when giving a fairly large amount of gas when warm at high rpm - it starts out feeling like it's running on 4-6 cylinders or timing is off - half the time it runs fine when cold, the other half either really sluggish and improves when warm, or it starts out slightly sluggish and improves when warm - for awhile I was able to clear the sluggishness again by giving a fair amount of gas at high rpm, like it was blowing something thru the inj's and clearing or unsticking - O2 sensors are coated with black carbon after awhile - I can usually tell when the computer has thrown a 44 again (after clearing the O2 code(s), and the 2 code 'power interrupt' is currently lit) - it gets slightly sluggish after driving for awhile, and the sound of the exhaust is deeper and louder

2) It cuts out occasionally, intermittently at moderate acceleration like there's a dead spot in some sensor - TPS? - I can usually power thru it - this is mainly observed when cold'er - happens maybe 5-6 times on a 1/2 hour trip - but will occasionally do it warm - it doesn't do it all the time, but the last two days it has

3) stalls at idle occasionally, either in Drive or not; this is mainly when warm (yes I've replaced IAC, cleaned, re-replaced with old, cleaned, cleaned again, and cleaned again) - I can usually get it to stay running if I very slowly de-accelerate - but it does it in neutral in the driveway after 2 minutes of just sitting there and running....

So, the Fuel pressure drops pretty slowly after engine is off, leading me to believe the inj's are not leaking much, but don't know for sure.
'have done the typical tune-ups with recommended manufacturer parts, done replacing/cleaning/verifying most all sensors, exception is fuel temp sensor, no vac leaks (at least external), vac advance is holding vac, cleaning of intake and fuel system over and over, fuel pressure 35-37, new alt', fluids replaced and look good, I have some very minor, typical leaks of various fluids with the exception of coolant; I have not tested fuel press reg, any injectors, timing as I'm not at that experience or confidence level yet. I've done the recommended electrical tests on the RAVE man'.

I'm thinking I may have a bad injector or two on the left, but I've also had the right O2 sensor pop-up as well - both are 3 mos old

The TPS problem, I've tried new, old and used TPS in it and the code never goes away - I looked into tracing down the wiring, but a large job that I'm not sure I'm confident in my abilities or patience to go the entire way with what it takes....that attribute in itself may eliminate me from being qualified for that or other jobs...

'hope you can provide a few efficient hints to try and boost my confidence to get to that next level of analysis - I have heard that there are certain gasket making products that give off a certain gas that causes the O2 sensors to 'throw' - I'm not sure what gasket 'glue' I used last time I re-fixed the plenum after cleaning - that I should check into, but don't have the tube anymore - aaagh! - I should probably spend the money on the real gasket and take this out of the equation if it is concerning, but don't know...

Signed, Part-time growing analyst trying to turn hobby mechanic, thanks in advance.

 

[alj]

Thanks,

I tracked down the idle problem - the IAC sensor was fine -
There was no gasket between the module the IAC was hooked to and the plenum,
and it was sucking air between the aluminum.
I finally was diligent to go all around the plenum thoroughly & slowly,
& I sprayed enough carb cleaner to discover this.

I still have my sluggish situation when running cold - I thought this was slowly disappearing...but it has come back stronger....
Today I found the #2 plug was wet when it was running sluggish,
while the others were dry and looked good - While sluggish, I ran it for 15 minutes
till it 'recovered' - I had to run it at pretty good RPM to get it to 'clear'....
And then I continued driving for another hour and good performance.
I rechecked the plug after getting back, and it was dry and clean.
'so maybe that one, and possibly other injectors are faulting. I haven't read how to clean
these manually / or rebuild if possible - I'm having to raise my confidence to a next
level to even considering de-installing it.

On the persistent left O2 code(s), I started tracing wires on the left O2 line,
and found an oddly very thick blue wire that had been taped (along with the two others intact).
That large blue wire is two wires in one covering, with one shielding wire around a central core wire.
The core wire alone is connected to one of the O2 pins on the connector.
The shielding wire is not connected to anything and thus the tape - it is a 3-pin O2 sensor.
I was able to get an ohm reading between the two blue wires (just curious), and it is showing some conductance.
I don't remember the value.
I don't know if this is significant, or wonder whether at one time it was a
4 wire O2 system re-wired up with this suspicious cable down to a 3.
Does the 95 take standard 4 wire O2 or 3?
Why would someone rewire a 4 connector O2 to reduce to a 3, if that is the suspected reason?
'cheaper O2 replacement?

Noteworthy, even when running well that last hour, I had 4 bouts of
hesitation happen (THIS shortly after two restarts, w/ two hesitations each time)
The hesitations happened when accelerating moderately. I have no idea what's going on here....
When it was running sluggish at the start of the test drive, I had the same
hesitation 2 or 3 times, but it was significantly more pronounced.

I hope someone can help me please?