I have a 1990 F-150 XL with a 5.0 and 5 speed trans. Power steering and power brakes and a/c. My question is how to keep it idling smooth, it revs up and down, also gets lousy gas mileage, 6-9 mpg, on a good day. but runs good when above 10-15 mph.
Any help would be appreciated
Thanks

 

Well, I would probably start with the IAC and cleaning the throttle body. I had an 88 5.0 and when it would idle rough a good dose of throttle body cleaner (including in the IACvalve holes) would help quite a bit. The EGR may also be causing some problems here as well. My truck would get 11-12 mpg no matter what so I am kinda lost there unless it is maybe an O2 sensor causing it to run closed loop all the time or something.

Just some thoughts.