so to start off i just got a new wiring harness installed at a shop. they put in a s13sr harness in to my s14 with a redtop sr20det for my power fc. the next day i got the car tuned. i drove the car home that night it drove great no problems. so im driving home from school and i turn a corner all of a suden the rpm just drop all the way down to 0 and then the car bounces back agin so i keep driving. then it starts to buck and then backfires along with droping rpm. it keeps doing it all the way till it would backfire once and then just die. also it started to die if i did not rev it every time. all this happend in a 5 minute ! any help would be great! thanks

That sounds like something is partly unplugged, like your cam-angle sensor, throttle position sensor, coolant temp sensor. Backfiring means either that the engine does not know when to fire (like if cam-sensor signal were being lost), or the fuel mixture is waaay too rich like if the coolant temp sensor signal or throttle-position sensor were lost).

http://zilvia.net/f/engine-tech/293028- ... guide.html

Sometimes if the pin of a connector gets bent or pushed in, it makes contact for only a little while, then falls off.

thanks ! i noticed that my ecu was not fully pushed in. i dont know if that fixed any thing im going to run a check list and check all the connectors. maf was plugged in along with the coil pack harness cas was plugged in.