Well, now a new problem has reared its ugly head.

If the car hasn't been started for a few days, especially if it's been relatively cold (meaning in the mid-50s F or below. I know, I know, that's not "cold"), the car's started acting up on first start of the day.

I put the key in, and crank the engine. The car will start immediately, like normal. Then, after about 3 seconds, it falls on its face. It stumbles, coughs, and dies. Subsequent attempts will usually just result in cranking, an occasional fire, but no start.

If it does this, I've found that if I hold the throttle in about half way, it will stumble, then start, and then the revs race up to between 3K and 4K and the engine runs. But if I let of on the throttle it will cough and sputter and die. If I repeat, and manage to keep it running at about 2K until the temp gauge reaches the first hash mark above the bottom, then the car will idle and not die, although the idle isn't as smooth as it becomes after the engine is fully warm.

After the first warm up of the day it never happens again. If it sits overnight it usually won't happen the next day. This never happened during the summer, but I have no idea if that was due to warm nights, or if it's just a coincidence that this started when the weather turned "colder."

I ran codes but they are equivocal. They show misfires on 1 and 3, but that's probably a symptom of the stalling, not the cause of the stalling. There was also a code for some issue with #3 injector circuit. I thought I had a pic of that code but I don't. I'll run codes again and see if it's still there.

So... any suggestions?

 

Posting a follow up.

A couple weeks ago I hooked up the scan tool and checked what the computer said was my intake air temp, and it was quite a bit higher than the actual ambient temp. More than I think normal heat soak would account for. I pulled the MAF and examined it closely. The front side of the IAT was covered in schmutz (that's a technical term) and the back side was clean. So, I cleaned it good with some MAF cleaner, making sure I got up into the actual MAF chamber, too. I also sprayed electrical contact cleaner on both halves of the connector. After letting them dry for about 15 minutes I reinstalled and started the car. The "sensed" intake temp was now very close to the ambient temp. A positive sign.

I have not been able to let the car sit for two or three weeks, so starting after that period of time remains to be seen. But even after sitting a few days the car fires immediately and idles correctly, dropping RPMs as it warms up. So... it looks like problem solved.

 

Well done. Gotta keep these MAF sensors clean. I spray them with MAFS cleaner at every oil & filter change. Still running the factory sensor....

 

I may have jinxed it. I got the vacuum leak fixed, the monitors all set, and I drove across town the other day on its longest trip since I replaced the O2 sensor. Everything was fine until I got the CEL. Ugh. I pulled off and scanned and now I'm getting too rich on BOTH banks.

I cleared codes, finished my drive, got back on the road, and eventually got the same codes again. It only happens when on the freeway, about 70mph or so. OK. rich on both banks, seems like a MAF problem to me. I probably should have replaced that thing on Day 1 of ownership.

I have new MAF in hand now, and will install tomorrow and drive around. Later on I'll install a new tail housing support. I noticed mine appears to be original and has collapsed, as have the motor mounts.