Banging back & possible engine vibration.
Banging back & possible engine vibration. Ok, i'll try & make it simple, the last 3 trips to the track i've been exsperiencing a vibration in 4th. gear under WOT of coarse, sometimes its not as bad as others, but i've noticed the cars been inconsistant on the ETs & MPH (60 fts. are dead on), anyways, this last time out was with the stock tune, as i sold off the hypertech, i did unload the program if anyone ask., well the car felt decent accually cruiseing around town, smoother too, so i went to the track last night to see how it fared over the hypertech & to take advantage of the cooler temps, well as i'm truckin down the track, everything feels great (was shifting at 5900), i'm in 4th. & at about 5000 when all of a sudden "BAM", the car hickups abruptly & it was a good one, enought to kick the car back & it still runs a 13.54 (a new best), as i'm rounding on the return road i hear pop-pop through the pipes & thats it, runs fine back to the pits, second pass it does the same exact thing & runs a 13.85 on the same 60ft., This is ONLY happening in 4th. gear 
, i'm sure the Opti/cap/rotor & coil are original, i wouldn't think a plug or wire would do that, i don't remember hearing any backfire through the pipes or intake when it did this, just a really hard hickup, this has NEVER happened before, only sence i removed the hypertech, what should i check? BTW, fuel pressure is good. I'm going to check for a vacuum leak tomorrow. Give me your thoughts.
, i'm sure the Opti/cap/rotor & coil are original, i wouldn't think a plug or wire would do that, i don't remember hearing any backfire through the pipes or intake when it did this, just a really hard hickup, this has NEVER happened before, only sence i removed the hypertech, what should i check? BTW, fuel pressure is good. I'm going to check for a vacuum leak tomorrow. Give me your thoughts. 
