1991 Ranger 3.0 automatic 162,000 miles

Ever since the weather has gotten colder my ranger has began to run rough.
It starts up fine and runs great until you shut it down, do a couple errands (5-10 minutes) and then restart. This is when the idle is chugging. It's almost to the point of stalling. If you drive off, it recovers and is fine like nothing happened.

I have looked for black smoke from the tailpipe and have seen none. This engine has been maintained and is tuned up 100%. All i can think is that maybe i have a bad sensor or the IAC is bad. The check engine light is not on.

Plugs, cap, rotor, wires, fuel filter, have been replaced within 2 months and i have cleaned the mass air flow wires. I have no EGR and i cleaned the IAC 3 months ago. The throttle body is clean also.

Any ideas are welcomed.

-hooD

 

Try pulling the hose off the fuel pressure regulator when the problem is occuring, see if it has any fuel in it, that would indicate a bad FPR.

 

Check the air tube that runs from the Mass Airflow Sensor to the Throttle Body for holes or cracks. If the air tube is OK remove and clean the Throttle Air Bypass Valve.

 

Where is the Throttle Air Bypass Valve located?

The fuel pressure regulator was replaced about 4 years ago when it went bad and black smoke poured out of the tailpipe.

I put a bottle of fuel injector cleaner into the last tank of gas and i haven't noticed the rough idleing problem. Do you think i had a clogged injector?

-hooD

 

The TABV is mounted to the upper intake its what you are calling the IAC, mounted with 2 bolts and 1 plugin conector. If you cannot find it do a search and you will find more info.