91sifreak

We just put in a Sohc Vtec out of a 94 Si hatch and put the 91 tranny on the engine and block (it went into a 91 si hatch), it all runs fine but when you punch it to get a good launch or you get above 4000 rpm in 4th and fifth gear it starts to miss. The engine will bog for a second and then it will come back up. Any ideas I have done five of these swaps and never had this sh*t happen???????help??????