i have an 89 hatch which i swapped heads with a 93 del sol (1.6L VTEC) but now my car will sometimes not go over 3000 rpms. does it have something to do with the VTEC? when i am accelerating, the rpms will go up somewhere between 3000-4000 and then bog down. this could be a big problem while trying to merge onto a highway. any idea what could this be?