Hello. Been having a problem with my engine surging at lower (school zone) speeds. Usually I am in 2nd or 3rd gear (M5 Tranny) trying to maintain the 20 or 25MPH limit and the engine will surge about 5MPH faster for a second or so, or at least till I let off the pedal. Cold or Hot doesn't seem to matter, does it in the School Zone a block from home and the one near work 15 miles away. It doesn't seem as noticable when I do not have the Air Conditioner on. I also do not notice the problem at higher speeds, above 35-40MPH.

Anyone know what may be the cause. Truck is a 1990 F150 XLT Lariat 4.9L M5 Tranny. If it were a Cadillac of the same age I would say it is the climate control switching the A/C compressor on and off to keep the interior temperature about the same .... but I do not think we had that in our 1990 F150's.

 

It might be a bad spot in the Throttle position sensor (tps). Look up the smoothness test for it, its not a hard thing to do.

 

Should I search for that here, or should I look in that wheel chock published by Haynes that I have?

 

http://fordfuelinjection.com/?p=30

 

Thanks .... Will check that out next wrenching session.