Idling/ Stalling problem

1990 3.1 liter. My memory became foggy due to my frustration with an overheating problem where, in a mad rush to save the day, I replaced the water pump, radiator, thermostat, coolant sensor, back-flushed the car several times, wrestled with the heater core, etc.

Here’s what I seem to remember. I repositioned a hose from my overflow tank (my tank has a second hose that apparently just vents to the ground, and thus attaches to nothing at all), after which the hose got caught in the pulleys and serpentine belt. You could smell burning rubber, and smoke came pouring out. I removed the hose, needless to say. I think that’s when my idling/ stalling problems began (the engine seems twice as loud and more strained since then, the engine is still VERY powerful but yet seems less powerful than before). As I said, however, my memory is foggy as to when the stalling/idling problem began. Maybe I loosened a vacuum hose without realizing it. Come to think of it, there is a hissing noise heard under the car, almost seems to come from the bottom rear of the car, perhaps near the gas tank, and I don’t know of any vacuum hoses way back there.

I’ve heard that a blown gasket can cause idling problems, but I have no bubbles in the coolant, no milky sludge in the oil cap, and no coolant in my engine oil. True, I’ve had a bit of steam or white smoke come out from the exhaust, but only twice in the last three weeks.

If my car will make it to Pep Boys Automotive without stalling out, I will purchase an OBD code reader today. My check engine light never comes on, so I think it's defective (or maybe a bad computer?).

Let me add, I wanted to detach the TCC connector, but I don't know where it is. I want to detach it because the idling sounds reasonably good in park and neutral, it's when I shift to driver or reverse that it sounds bad. The SOUND of the idle peaks and falls like a roller coaster. That is to say, the sound surges for a half-second than plummets for a half-second, and so on. But even though the SOUND peaks, I don't really geta "power surge," so I wouldn't really say that it "idles high." Thus the peak point is not really "high idle" but rather normal idle, as far as I can tell.

First thing I would check is to make sure your ignition system is in good shape. If that checks out ok and youre suspicious of a bad head gasket then do a compression test. If those check out ok, youre left with most likely a fuel/sensor problem. The computer can store throw a code and still not turn on the check engine light.

Did you clean all the sensors in the throttle body. All my problems cleared up after I did that.