Greetings, I have a 1987 E150 van with a 5.0 EFI engine. When I first start it up it runs fine on fast idle, but when the idle rpm drops down to normal speed it starts to fluctuate run fast, then slow, fast then slow. It runs great going down the road though... I have already cleaned the egr valve & the Idle speed control bypass valve, but this did not help... any suggestions? thanks, mike-

 

Exactly the same engine and same problems for me... waiting for help

 

did you check or repace the thottle position sensor(tps)?

 

No I did not... Where is the tps located? Thank you very much for the info...

 

you will need a Haynes book. It is on the end of the shaft that holds the throttle plate. Also do some site seaches for "TPS" and "throttle position sensor". And please when you fix it, post the cure so the rest of us can learn.

Chris

 

Mine hunts at idle too, have replaced EGR, TPS, IAC, temp sender to PCM, tried different MAP sensors, O2 sensor and never stopped it. It'll hunt for a couple of minutes, then straighten out.

Am gonna cure it soon enough: have a 78 351 with an Edelbrock Performer intake & a Holly 600 4bbl to go in there instead!

The TPS is the small black plastic piece on the left side of the throttle body (as you look in under the hood) with a 3 wire connector. It's non-adjustable on our models, but you can clean it. If you have a meter, set it on ohms, then slowly depress the gas pedal & you should get a nice steady sweep with no dead spots.

Another good thing to try is to look at the black & white connectors in there around the tranny dipstick: they're known for going bad.

 

Thanks for all the help... I will keep you all posted on my findings...
so far everything that I have worked on has been difficult as hell, these vans sure are a character builder...Mike-