revolutionmusclecars

New to the forum and I hope this is posted in the right place. I have a 57 bel air with an 89 corvette tpi, map speed density setup. I'm having issues driving it. the symptom is very little power under load past 1/4 throttle and intermittent pops through the intake. The fuel pressure is 40 steady with fpr disconnected. I pinched the return line and it shot up to 60 till I let go. I have checked for and not found any vacuum leaks. It revs fine in neutral but under load it does not want to accelerate. Thanks for any help you may have to offer!!