1996 Ford F-150, x cab, 8 cyl, auto, 2wd, 131+K miles. Intermitent idle hesitation at stop lights and intermitent rough ride. At 128k Miles changed out IAC valve. At 131K Miles pwr cln carb, throttle plate, new battery. Had new plugs, wire, fuel filter, dist cap, all done at 112K miles.
After all this, idle still runs down at stop lights to the point of stalling. When restarting it acts like its flooded, also runs rough at speed. This is VERY intermitent, it will run great for days, then act up. It mostly occurs in the afternoon after being parked all day. Additionally, sometimes hard shifting from first to second gears.
Is there a fix, what should I check next?
My mechanic, whom I trust, had it for four days last week, on the computer and test drove, including to home and back, for over 140 miles and no problem. He could not get it to throw any codes. Even after disconnecting mass air handler-which he said was clean.
Help. I like the truck and it suits my needs, but this is very frustrating and getting expensive.