Hi, i have 90 civic ef with a b20b vtec swap that i bought off some one my friend knew. the car was working good and all until it wouldnt start. After much searching i came to find out that the ECU was burned out. So i look over some froum threads on other websites and they said that a pr4 ECU would work with the build the car came with. So i got a pr4 and i sent it to get socketed and chipped for a b20 with b16 heads and vtec. i plugged in the ECU and for some reason the vtec wont engage the engine just seems to stutter at 4000 rpms like it wants to turn off. Can anyone please give some insight on this, its my first time messing with the electrical on a car. Maybe i made some mistake when i sent the ecu to get worked on? i have the receipt on what i paid for, just ask if you want to take a look. Thanks for anyone's help.