Hi everyone.
first time posting. I have been having weird idle in P and N also when decelerating. Truck runs fine plenty of power. Idles fine when in gear also idles normal in P/N when AC is on and when i disconnected power from lift pump. I do have mods on the truck and to me it seems like a fule problem im suspecting FPRV it is stock. Any imput would be appreciated its driving me crazy

 

Any suggestions before i start throwing more parts at it