stupid truck

[myold96]

my friend bought a 91 exploder from a used car lot the p.o. looked like they spent a lot of money on the suspention but none on the engine the head on the d.s was cracked or at least the gasket was shot so we changed heads hooked everything up like the haynes book said fixed a bunch of vac lines because they looked suspect got them all hooked up execept the large one to the cruise control activator so i capped it off everything else is hooked up and it starts great sometimes it idles shooth and others it doesn't did tune up ,new coil pack,new brain box, everything i can think of and it doesn't like 4 hi but i think thats just an activator it has plenti of power just sometimes a bad idle and it leaves me scratching my head and telling the vehicle about it's parents, and telling henry ford to climb back under the porch with his mamma then i walk away for a while and come back the next day help

 

[RangerSVT]

Irratic idle could be several issues from a bad fuel filter, dirty injectors, dirty maf, dirty air filter, dirty/clogged/bad iac valve to a malfunctioning/mis-adjusted tps sensor. Start with the wear items, fuel & air filter, clean iac & maf sensors (do a search for cleaning the maf, its a delicate procedure). If you still have irratic idle after those, then the tps probably needs adjusting or replacement...

SVT

 

[PetesPonies]

I agree, clean the TB, clean the idle bypass and set the idle as per Ford.

 

[kimcrwbr1]

Get a length of vacuum tubing and search around for vacuum leaks. You should have between 17-20 inches mercury at an idle. use the vacuum tubing to search for leaks just be careful of moving parts. Put one end up to your ear the closer you get the louder the hissing when you find a leak. Did you run it with any of the sensers disconnected if so disconnect the battery for 1/2 an hour while you clean all the connectors with electrical cleaner and use dielectric grease when putting them back together. Did you put the engine to chassis ground wire back on to the firefall. GL

 

[adsm08]

Hook a jumper cable from the engine block to the battery negative, unplug the O2 sensor, and unhook the cats.

Coolant damages oxygen sensors and cats, and either of those could cause your problem. Also, a bad or intermittent engine ground could cause it.

I can think of half a dozen other things as well, but let's start with the easy stuff.