Truck will not stay running - stall at idle?

Alright, the idle adjustment didn't change the problem same clunking at idle, I set the butterfly slightly open with the screw and did a voltage check on the TPS. No dice. I'm going to take the IAC off and check for movement, after that I can only assume EGR or bad injectors.

One strange thing it does is, when the gas is touched the RPMs jump about a 1k and stay there for a few before it drops back down to a death chug.

No codes until the engine dies.

1991 Ford Ranger 2.9; stick, 105,000 mi. The clutch safety switch broke. I had to move the truck out of the driveway. I used a wire to bypass the switch. I bought and installed a new switch. Now truck starts but won't idle and check engine light is on. I have to pump the gas pedal to keep it running. I know I screwed something up when I bypassed the switch.

I know that much. Since I don't have a codes reader I was looking for something more specific.

Problem started over a year ago. 3.0 L Engine idles extremely rough, or not at all, when started cold. The problem disappears after approx 60 secs. Then starts fine the rest of the day. I've found I can shorten the duration of the problem if I start and immediately force the rpms to 1500 or greater for about 15 secs. Last time I checked (6 mos ago), there were no computer codes. I've replaced the IAC, fuel pump and filter, cleaned the MAF sensor. Symptoms are very much like the Ford 4.0 L problem which requires a timing belt tensioner and new lower intake manifold O-rings/gaskets. I put in a short block in 2004, around 125,000 miles; this problem did not begin until late 2007.

Thanks

Chip Wiggs

I checked the resistance on the ECT (7.6k ohms) and ACT (10.9k ohms). Truck had been at operating temp for a hour and then turned off for an hour. Ambient temp was around 84 deg during check. One of the latches on the ECT connector was broken off. My plan is to replace the ACT, ECT and ECT connector, and then clean the carbon from the intake as far as possible past the throttle plate as reasonable. It will not be until the tomorrow morning until I know if the problem is corrected.

Thanks to both Docfixit and merlin2021 for your replies. I will update when I know more.

Chip Wiggs

Replacing the ECT corrected my problem, the ECT connector was slightly damaged and may have contributed to the problem by not having a reliable electrical connection. I replaced the ECT connector also. I replaced the ACT sensor this morning simply because it has 155k plus miles on it.

Thanks for the help!

Chip Wiggs