Rough acceleration

[duckdog27]

I have a '94 XLT with 175,000. Recently I have had the problem of rough acceleration/idling after driving for a while and shutting the engine off. To be more exact, I drive for about ten minutes, park the truck and turn off the engine, then return ten minutes later and start up with rough idling and when I put it into gear it accelerates very rough. Any suggestions?

 

[LukeDog3D]

start out free: pull a couple of plugs out and have a look at them. Check the gap. See if the air filter is dirty. Check for vacuum leaks. Check for arcing in the plug wires. Test the coil with a voltmeter (see shop manual). check the PCV valve. Clean out the throttle body. Make sure all of the electrical connections are plugged in. Clean the Mass air sensor. Any oil in that radiator fluid? Reset the computer.

then move to cheap: replace the plugs, air & fuel filter; plug wires if they look crusty. replace the PCV valve.

after cheap, start on the stuff that costs more; o2 sensors, etc.

 

[MrShorty]

Along with the other "free" stuff: Check the vacuum line that feeds the fuel pressure regulator (FPR) just after shutting off the engine. If you detect gas in that vacuum line, the FPR is almost certainly bad. Check the fuel pressure (Guess this becomes "not free" if you have to go buy a pressure gauge). In particular, you're looking to see if the fuel rail holds pressure after the pump shuts off. Your symptoms seem consistent with a leaky fuel pressure regulator/leaking fuel injector allowing excess fuel into the manifold after shutting down.