97 discovery intermittent no power

Hey all, New discovery owner here. I'm a mechanic by trade, ase certified in electrical systems and advanced electrical diagnosis, so ihopefully won't need too much help, but the problem is that i don't have a scan tool at the moment, especially not one that will do live data or manufacturer specific codes.

So, now that that's out of the way: the car drives fine until it decides very suddenly that it doesn't want to. In the 800 miles since i bought the car, it's done it twice, once right after a warm start, once after pulling into a parking lot to turn around. The car acts like it's starving for fuel, it's not a spark related misfire, there's no sharpness to it, it just falls on it's face if you try to give it any gas, and it doesn't have enough power to go over 25.

The first time it happened, i was in a residential area. After driving like this for a mile or so with no improvement i started to smell that lovely rotten egg smell of overheated cat, so i pulled over, turned it off and checked under the hood. I didn't see anything obviously wrong, so just for giggles i pulled the maf plug and tried to start it. It started and died, i tried again with a little throttle, and it stayed running. A quick test drive showed more power than ever. Ok, so far so good. Idrive home with the maf unplugged and it makes it no more problems.

Fast forward thru a cat replacement (it was rattling badly and driving me nuts) and new plugs (because **** Champions), i bought a new chinabay air meter because it was cheap enough to warrant having on hand as a tester, which iended up installing along with a new air filter.

The second time it did it, it was after the new parts, and this time pulling the maf plug made no difference, i had to just pull over and wait twenty minutes. Both times it happened, the only codes stored were misfires. The heads and timing cover have obviously been off pretty recently in terms of miles, but the car was in storage for two and ahalf years because the PO didn't want to throw money at diagnosing the car when his wife wanted a new one anyway.

So. As far as things that can suddenly go **** up and cause a problem to come and go? Shorted wiring? Crank sensor? How did I just put 450 miles on it in one day and stay off the hook? I have a good multimeter with me but not much else, unfortunately no scope or i wouldn't be typing this novel on my phone. Any ideas are appreciated.

How many miles on it, any fault codes, if so what are the fault code numbers?

154k, i think the codes were p1313 and p1314.

Oh, and it had p0420 before i had the cat swapped out, and i know that i need to do the spark plug wires, i sprung a tiny leak from a heater hose and it sprayed the coil, i could hear the wires arcing all over. What brand of wires do these like? I've always liked ngk or bougicord best.

Well I just took it out for a drive, made it about a mile down the road before it flaked out again, and right before I pulled into the drive way it was back to normal. By "the road" I mean a nasty, rock encrusted dirt road that goes about six miles from my driveway to pavement. I just went out to warm it up and check cts resistance, and it took three tries to start, that's new. Once it started and warned up, the hot resistance was ~300 ohms which looks right on according to the graphs I found. It might also be worth noting that the plugs itook out were relatively new (5-10k on them tops) and were all even in color, but the ceramic was unusually white, with no deposits on them, and just alittle soot around the ring.

I once worked on an older bmw that was acting similarly and after a lot of wasted time it ended up just needing a cap+rotor and some plug wires, and it's problem also basically came and went as the car got fully warmed up and driven.