After track, car runs like S**T.
 

I have a 351W with some mods done to it. My best time was a 14.665 @ 95.9mph. That's with 2.73:1. After getting 4.10s I was told I should lose a full second with 3.73s so with 4.10s I should lose that second for sure. I didn't even lose a tenth. I don't care how bad my 60' time is, 2nd, 3rd, & 4th pull a lot better, so why the hell did I only get a 14.590, my speed went up to 96.7mph though. Any ideas. My 60' times were around 2.2-2.3. Also a couple of days before going to the track, my car started to sputter on every gear below 2000rpm, after the track 1/2 way home, it got terrible, I don't even want to drive it because it's so bad, the whole car shakes, I know it's the engine because it does it in neutral when I rev it a little, I put brand new plugs in, checked all the wires, checked the tps, I don't know what else it could be. I'm going to do a compression test, & a leakdown test, & see what'll come up. Any ideas?

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89 coupe, 351W, 351W heads, 30lb injectors, 190lph pump, 80 maf, 70 tb, ? cam, cobra upper, gt 40 lower(14.6at95mph)