93 Ford Taurus Hesitation

[bababooey]

I am not sure what the problem is but it doesn't happen all the time. First I had a tune-up. That helped. But now every once in a while I have hesitation. I have put fuel ejector cleaner in the engine. But once I was hitting the gas and it would not go over 30 mph. Then I would start the car and put it in reverse and the car would stale out. But the next time I started it would run fine. I have taken it to the shop and they aren't sure either. I am going crazy. Any suggestions?

[ABE]

Does the "check engine" light come on at all? Have you had the computer checked for codes that have not set the "check engine" light on?

[bababooey]

It has. I had it checked and it came up nothing. The check engine light does not really come on that often though.

[ABE]

The areas that I would look at first are related to engine idle speed and air/fuel ratios:

1. Check all vacuum hoses for cracks or loose fitting
2. Idle air bypass valve may be sticking. It sits on the throttle body and has a round body. The computer controls engine speed by moving a pintle inside the valve to limit air flow past the throttle plate.
3. TPS (throttle position sensor) can be tested for sensor voltage <1 volt to 5 volts. It can give false reading to computer leading to lean fuel mixture and hesitation (had this on '91 Mercury).
4. EGR (exhaust gas recirculation) valve should be closed at idle but may be carboned up causing sticking and air bleed.
5. MAF (Mass airflow sensor) could be dirty and not giving an accurate reading to computer
6. Low fuel pressure due to worn pump or sticking regulator, pressure should be about 40 psi

Hope this helps