Toyota 89 SR5 truck..-engine stalls?

Toyota 89 SR5 truck..-engine stalls?
Hello, My 89 Toyota truck 4 cyl EFI, starts good, but while idiling, backing out and some times at a stop the engine stalls. Also when driving I notice that the RPM drops intermittnetly like missing a heart beat. This is not happening all the time. I took it a repair shop. While they had the vehicle the problem didn't occur. I tried adding cleaning stuff to the gas but didn't solve the problem. Spark plug and cables checked out okay too. It has become a safety problem. Please help. Thanks I don't think it matters if the engine is cold or hot.


Answers:

Chosen Answer
brian h:  you might have a bad fuelrelay switch or o bad o2 sencer
2006-05-22 13:21:36
rock2001wwf:  My corolla has this problem too, however, my car doesn't come with the RPM meter. I have tried many things, change fuel filter, tune up stuffs, coolant temp. sensor, oil change, transmission fluid change, coolant flush. But no use. Right now I am thinking maybe the oxygen sensor, because if this thing is old, the carbon will cover the sensor, thus give the main computer wrong info about the air/fuel mixture. Before you buy this thing, try to check all the vacuum hoses see if there any leak. Furthermore, if you change the sensor, please tell me if it working. Onemore thing, if your car automatic,try to drive above 45 miles per hour,say 47 to53, and then stop the car completely, if the problem occurs, that means maybe the TCC solenoid is bad. At least that's what I heard. Last thing, when you come to a stop, if the engine begin to shake like it is going to stall, shift to parking or neutral, and release the brake pedal see if this help. Whatever the result is let me know. Good luck.
2006-05-22 13:26:37
bobweb:  I would clean the throttle plate and bore with a tooth brush and household spray cleaner. Make sure to remove the carbon deposits on the back of the throttle plate. Your Idle Air Control (IAC) valve and passages may need cleaning also. This should be done periodically as preventive maintenance and you can do it yourself. However, some vehicles may have the Mass Air Flow Sensor (MAF) mounted right ahead of the throttle plate which makes it hard to get at the throttle plate easily. Another thing to check is that your EGR (Exhaust Gas Recirculation) valve isn't being held open at idle by carbon deposits which would cause a lean mixture and stalling. When you remove the EGR valve for cleaning, clean the associated exhaust passage ways too. However, the RPM gage is hooked directly to the ignition system, and if it drops quickly as you describe, your ignition has an intermittent fault, possibly a sensor or ignition module going bad.
2006-05-22 13:48:53
whatmarc:  I know I sound like a broken record, But look for vacuum leaks, also the make sure the duct work going to the intake manifold is tight and not leaking any unmetered air.
2006-05-22 14:26:15