87 Aerostar idles erratically

[Riverrat203]

I have a 87 Areostar with 197,000. I has a 3.0 engine that runs well, but has developed an idle problem that acts as if it's going to stall, and then picks up speed and smooths out. It does this repeatedly, and tapping the gas pedal will cure it for about one minute, then it reverts back to rough idle. Some loss of power occurs during acceleration but corrects itself with surging... I have replaced the idle air soleniod valve and the throttle position sensor. I don't believe there is a MAS sensor in my vehicle. The cap and rotor are new. What else could be the likely culprit? It seems to be electronic in nature. Thanks for any Ideas.

[Riverrat203]

After replacing the idle air control and the throttle speed sensor, and today the map sensor, I was out of ideas. I still had a coughing and sputtering engine at Idle...I decided to take off the Idle contol valve and spray the passages of the throttle body. Found some sludge in there. Seemed to improve things a bit, but no cure. Then I happened to talk to a mechanic who asked me if I had tried disconnecting the battery for at least 10 minutes so that the computer can rid itself of bad codes, and relearn the new sensors. Of course I hadn't done that.
When I got home i tired this and it seems to have corrected the problem. As of now it's running smooth as a babies bottom. Lucky for me, I have only put out a total of $15 for these parts in a junk yard. My own labor is worth far more!
I guess the point is that when you replace a sensor or electronic part, you should always reboot your car's computer.

[Davescort97]

That's exactly what I was going to say. The computer will go back to default values and then relearn new condiltions as they occur. I'm fairly certain that the parts you installed were needed, but the computer hadn't recogized them yet. I've had some people tell me you don't want to do this because it will erase codes the dealership needs to correct your problem. I don't agree with that. If there is a firm code it will come back on the CEL.
btw. the dealership charges $85 to do what you just did. Good for you.