I have an 04 that recently had a rebuilt engine installed less than 5k miles on it. It is currently surging with no CEL when held at a consistent rpm for over 30ish seconds. It has new injectors (less than 10k miles on them). If I’m in park and start it up it idles fine and if I run it up to 1500rpm it starts slightly surging until it starts missing. I’m really not wanting to take it back to the shop if I can avoid it. Any one have any where I should start.

 

Which engine? 04 Heritage or new body style?

 

new body with the 5.4

 

Has the fuel filter been replaced lately?

 

Also check the FPDM for corrosion on the back side.

 

Fuel filter was changed and it did not help.