Car not running what is should, need help.

:( Here is the low down on my car: 68 dart, 340 auto, 3800ger
converter, 410 gears, bfg drag radials, ss springs and comp.
engeneering drag shocks. Motor is 30 over with trw forged replacement
pistons, heads are not ported, 509/280 MP mechanical cam, cheapie
headers, edelbrock air gap and 750 Holley DP.I have the new MP electronic ignition kit in it with 20 degrees initial and 16 in the distributor and no vacum andvance. Last year with old dirt tires and tm5 single plain and old avs it ran 13.4@101mph, 60ft was in the 1.95 range. Got it to the track on Friday to get jetting right and ran 13.7@97mph 60ft was 1.90. I did get a little wheel spin off the line with the tires at 16lbs, ran out of time to try 14lbs. I tried shifting at 6000 and 6500, but no difference. I go thru the traps at 5500-5600. My only guess is that the conveter is junk and is getting worse, I have not heard anything good about them.Anyone have any ideas on what else to check before I buy a new turbo action converter?