I have a 2005 Aveo, SVM Manual transmission 179K miles. For about 2-3 months now I've been trying to nail down a pretty big issue that I've been having. Sometimes while driving, the car will suddenly lose power and/or stall out. It will drop RPM's, start bucking pretty violently, and slow down sometimes almost to a crawl. If I let off the gas it will completely stall, but if I keep on the pedal it will eventually recover only to stall out once in neutral or making a complete stop. Recently it seems to mostly happen once I let off the gas and cruise to a stop. When it's having issues it will drop down to very low RPMs at a stop, almost as low as 100, for a few seconds then either stall or jump back up to 800-1k.
I will go a few days with no problems, and then one day it will happen over 10 times on my commute.
The oil pressure light seems to usually be the first light to light up when it stalls. CEL hasn't turned on, but checked to make sure no codes were thrown and none were logged. I've rented a fuel pressure tester and drove it around for a while but didn't notice any drops in pressure, but it didn't ever stall when I had the pressure tester hooked up to it. Perhaps I'll rent one again and hold onto it for longer and see if I can get it to stall while I have it hooked up.
One day it wouldn't start, there was no spark, checked the Crank Position Sensor (Which was replaced a year prior) and found a green corroded pin on the plug. Sprayed it with WD40 and it fired right back up. I replaced that and it seems to have gotten a bit better, but if anything the frequency of the issues has just gotten less. Also replaced the oil pressure sensor and the fuel pump relay.
I've read in similar threads it could possibly be the downstream O2 sensor, but I don't want to keep throwing parts at it in hopes of a resolution.
This forum has been a giant help in the past, If anyone has any troubleshooting suggestions I would love to hear from you. The car is dangerous to drive, and I would hate to get a new car for a silly little problem like this. This community has been awesome, I hope someone can help shed some light on my problem.