1997 F-150, 4.2L, 120,000+. After truck warms up, idle still seems high and
truck runs rough at all speeds and idle. Feels rough during acceleration.
Sometimes when shifting from 1st to 2nd and from 2nd to 3rd, engine surges
for 2-3 seconds after backing off accelerator. When stopped at
intersection, sometimes engine will idle high and sometimes will drop down
to near normal. I've replaced plugs and will replace wires today. O2
sensors were replaced six months ago. Pulled off EGR valve and found no
blockage. Pulled IAC and it looks OK, saw no blockage. After replacing
plug wires, I'll check the spark at the coil. The TPS is attached with two
Phillips head screws that are EXTREMELY tight and I could not get them off
to check the sensor. How can I get the TPS off without damaging it, or
should I just try to drill the screws out and replace them and the TPS?
Can I spray throttle cleaner in the IAC and brush it out with a small
toothbrush? It doesn't seem that dirty, but maybe there's something in
there that I can't see. Anything else I should check/replace?