I have a2004 ranger lx with 2.3L ; Ive owned for several yrs but dont drive it much, only around town. my son recently borrowed it to drive for work about 50 miles daily. after a week I get a call that hes on the side of the road. it started running rough and lost considerable power. when I arrived I started engine and idle was terrible. stepping on the accelerator would not raise rpm. there was no check engine light on. while doing this we both heard a pop from the engine area, it sounded mechanical to me, then the motor immediately revved up so I let off the gas. and it settled down to a smooth idle at 800rpm. I was wondering about a stuck egr valve?