Time after time year after year we see deals like this--it always comes down to throttle blades 3/4 way open - lash way too tight is a good one ( you see--these modern computer created crap lobes with inverse radius etc have the lowest spot on the cam somewhere other than the back of the base circle--Surprise!! )-7 volts to fuel pump, 7 elbows in fuel system, WRONG converter, etc
It is a rare day when it is the cam.

Had a 500 inch running 5.50's right off the dyno--three weeks later running 5.90's after the customer replaced a ton of parts he got mad and sold it--one week later in similar car was running 5.50's again--Verdict--lash was too tight--simple as that

Check the simple basics--look at the data you have from your timeslips--the answer is there.