I recently purchased a 2002 Jeep grand Cherokee Laredo 2WD 4.7L V8 150k Miles.

It is an Arizona car with a straight body and decent interior but bought it Not-Running.

Needed a battery, done. Starter motor was dead, done. Then crank but no start. Replaced the crank position sensor and started to get it to hit and sputter.

The unit will start with a little throttle but misses, stumbles, shakes badly with a good bit of top end clatter and valve train noise.

I researched the forum and internet and found a good bit of info regarding rocker arms and lifters. I pulled the valve covers and thought for sure I would find a rocker out of place, but not the case.

The heads look "too clean" to me. Upon inspection, I think it has had heads replaced in the not so distant past but perhaps not right before selling. I did notice that all rockers were in place and on the passenger side there appear to be 3 rockers that are different looking than the rest. The original, oil stained and used looking rockers all have a relief hole in the top where they meet the lifter, the 3 new looking ones appear to have No Hole.

My concern is if the wrong rockers are in those positions, for instance a solid style rocker vs. a hydraulic style rocker, what would happen or be my symptom? OR perhaps these are just a new style rocker and look different because the truck is 17yrs old and parts change and are updated.

I also wonder if there could still be bad lifters that aren't pumping up that cause the clatter and even perhaps poor running because valves are not opening to their full potential.

I was hoping for suggestions on next steps in trouble shooting.

Thank you,
Stephen