What is wrong with this combo

A few of you asked me about my combo in my Dart. Well I am kind of sick over it, I have spent a lot of money to keep going slower. I had an 80 Mirada with a W2 372 inch engine, 11.3 comp. 590 lift mopar solid cam,victor jr intake, 830 holley, 4800 converter, 999 trans, 4.88 gears, 11.5-29.5 slicks, and a ladderbar coilover suspention,car ran 10.8 at 123 to 124, it wieght 3360 with me in it. My Dart combo at this time is 416 with 10.4 comp. indybrock heads ported by shady dell( they flow 313 at .700 int. 222 at .700 exh. the W2 flowed around 290 int. 190 exh. at .600) they also ported the victor jr intake to match the heads, and spec out the cam for the combo,.668 lift int and exh,[email protected] int,[email protected] exh,108 cl 104 installed roller cam, a tricked out 850 annular booster holley, 833 4spd, 4.10 dana 60, cal trac bars and springs, 8.5-26 slicks(both cars cut 1.50 60ft. times). Best time so far with this combo is 11.15 at 119, at the track sunday the car slowed to 11.5 at 116, 60ft were off poor traction. The car went 11.14 at 120 with unported heads,rpm air gap,the 590 cam,and 750 holley,3.90 gears. The car is run through 1 7/8 headers and 3 inch full exhaust. Do you guys think the cork in this thing is the exhaust or some thing else!