The car has always had an issue with randomly stalling and dieing. It could be coming to a stop, driving down the st or just in idle. No warning, usually except once in a while the RPMs will drop pretty low before it cuts out. Other times it will “stutter” if you wonna call it that while I’m driving rev up and down around 2k. Now while it’s doing that, I noticed if I give it more gas it’ll act like it’s gonna cut out until I let off the pedal then it revs back up and sometimes if I catch it at the high point and hit the gas again that will occasional “catch it” and it will run okay for a bit. Anyway - recently I found that if I just let the car warm up before I drive it seems to run great. If I just start and go, it dies as soon as I put it in gear.
Note: Maintenance up to par, no engine light, don’t smell gas, new filter, MAF, IAC, no vacuum leaks I can find.
One thing that can cause this is a faulty coolant temp sensor for the computer.
If the sensor is telling the computer that the engine is in the closed loop mode (hot), and not in the open loop mode (cold), when the engine is started cold, the engine will run too lean until the engine warms up.
Is the idle speed significantly higher when you first start the engine in the AM, then it slows down after about 5 minutes, as the engine warm up? That’s what should happen. Since you are only having this stalling problem when the engine is cold, there must be something wrong with the system that is supposed to boost the idle speed for cold operation. It might be the engine coolant temperature sensor isn’t working for some reason. If so the computer couldn’t determine that the engine was cold. But that should flag a diagnostic code. It’s possible for the CEL to be off but there still be stored diagnostic codes, so that’s the first place I’d look if I had this problem.
Does this car have an idle adjustment screw? Around that time that feature was removed from most cars, the engineers figured it wasn’t needed and its better to just let the electronic gadgets like the IAC control the idle speed, but maybe yours has it. If so, maybe all that it needs is the idle rpm adjusted.
Another idea is that your engine is running lean for some reason, and that would usually be caused by a vacuum leak. The symptom where you step on the gas and the engine seems about to die, that’s common with a too-lean mixture. Checking for vacuum leaks is best done by someone who’s experienced with how to do it. It’s more involved than just looking for cracked vacuum lines. Try to find someone who know how, and let them show you how to do it. If they don’t have a hand-held vacuum pump or equivalent, find somebody else.
Another cause for too-lean operation is a fuel pressure or clogged injector problem. A fuel pressure test would be the first step. There is a test to indirectly measure fuel injector flow too. I forget what it is called, but you pressure the rail, then turn off the fuel pump, and pulse the injectors one by one a certain number of times, then measure the drop in fuel pressure.
+2 to Tester.
In addition to his comment, the temp sensor doesn’t always cause a fault code. The ECU has no ready way of knowing the temp sensor’s signal is wrong. It has nothing to compare it to.