So I made the first investigative attempt by installing another FPR and that did not fix the issue. Next up in the coming days will be as Fitz suggested. I removed the TBelt cover and the belt is still taut and the cam sprocket still tight and in place. The symptom is predictable. When stationary and idling if I advance the throttle there is a hesitation ( stutter if you will , backfires occasionally also). Once pass this "point" the engine will rev smoothly and keeps the revs. It seems to me it occurs when there is a "demand" . I'll follow up for sure , thanks everyone and keep em coming!!!