When I start my truck (any time of the day) the idle starts at about 1500 rpm & drops to 500rpm, a couple seconds later it repeats but now to 2000rpm and back to 500rpm and continues constatnly. It does it if the engine is hot or cold. I have to be really carefull when shifting into drive or reverse cause it jumps forward or backward if I shift & the rpm's are high. It also started to jump when stopped @ a light or a sign. Does anyone have a clue what the problem could be?

 

Classic 2005 4.7L problem. Good luck figuring it out.

 

Thanks for the help.

 

Check your vacuum hose. Have you run a diagnostic test? You may have a bad sensor.

 

When I had my 02 it had kinda the same problem. It would happen at the worst times.Sitting at a red light or behind someone in traffic. But the RPMs would drop and almost stall then over correct and lunge forward. The dealership had a flash for it. But then it never really idled thesame after the flash