904 Problem

The 1'st gear breakaway and reverse are fine. It flare's up when you leave it in drive or shift it manually.
The engine is a mildly built 373 ci with maybe 325hp.
One thing I forgot to mentition is I also had the low gear set installed and input shaft and front 4 clutch drum from a newer trans to have the correct spline count for a new converter.
I did adjust the bands per Trans Go's kit.
I adjusted the stock linkage so that at wot the linkage is almost all the way back, with a 1/8 inch gap between the carb stud and the back of the linkage slot.
So it sounds like I have the linkage back as far as it will go. I'll try shorting up the linkage 3 turns at a time and see if it gets any better.