Michael St-Cyr

I have a ford f150 2004 5.4 triton 3 valve

of that I start the truck, the rpm goes up and downbetween 800 and 1000

When I give gas, rpm should not exceed 2000 and theengine wants to stop

I changed the pump gas, pump, throttle body module. The GST seems to work. It isworse than before.
I do not know if this is a spark plug problem?

Zrock

have you pulled any codes? would have been worth the money to pay a shop to put a reader on it and give you the codes instead of throwing parts at it. With the rpm bouncing like that i would almost bet you have a vacuum leak. my 97 had a surging idle and i found a rubber elbow rotted right out. Was hard to find. If you have a propane torch you can use that to find it