Thanx tommud & TJKJ for responses to last post. i checked all you suggested, even replaced speed sensor and wiring harness for same. Speedo still bouncing erratically when driving/maintaining constant speed manually.
i'm stumped. Thinking PCM may have issue but it's a SWAG at this point so if any further thoughts i'm always grateful. BTW, i do have scanguage and it has never given any DTC for this problem (which of course adds to my confusion).
Question

Thinking of salvaging PCM from scrapyard to swap out & see if any effect. Would the salvaged PCM have to be from a 5 speed or will any from an '04, 3.7L do?
i REALLY do not want to turn it over to any stealership! Had nothin' but bad experience w/them and just DO NOT want to go there so again, any thoughts are appreciated.