67 twin turbo dart

Before the dyno I would start it up and idle and rev a little bit nothing high, but would let it get to operating temp for a bit, would do that every weekend.
Every weekend? What was the purpose? Especially if it wasn’t tuned. I don’t start mine unless I’m driving it, loading it on a trailer or such. My buddy did the same. Several stuck injectors and washed all the rings out. It still made 1500whp on the dyno. I doubt that’s your issue.