my truck has always (I've owned it for 9 years) loped after start up "THEN" you put it in gear fast.
starts up smooth, no lope, put it in gear fast, it lopes.
all you have to do is let it idle for 3-6 seconds before you put it in gear. all is good, no loping.
i have over the years have changed every sensor for one reason or another, crank, cam, MAP, the VP, TPS, the list goes on.
the only thing i haven't changed is my ecm.

today it loped after i put it in gear every time after it had been running for awhile. womp, womp, womp, womp, then clears up and idles smooth. i put it in nutural at the drive through, back in gear and womp, womp..........for a second or 2

any ideas?

fuel pressure 17, filters are BFN, good fuel..........................

 

it fixed it's self, quit doing it for now?

 

mine did it and it was the fuel control actuator, FCA. Genos has them for about 120 dollars, three bolts and a plug. Mine is all better now

 

my 03 has a FCA, the 99 don't. it has a VP$$ fuel system.

like i said, it has loped every sence i owned it when you put it in gear fast without letting it idle for a few seconds. if you put it in reverse fast it will not turn on the lift pump either, no fuel pressure in reverse in the same situation. just let it idle for 2-3 seconds first, all is fine.

crazy truck huh?

 

Don't feel bad, mine lopes when you let off the skinny pedal and are slowing down to a stop

 

it has to be something with the fuel being injected electronically or the injection timing jumping around I'd guess.

it is still running fine today. it did it just 2 or 3 times Monday morning in BK's drive through??