I have a 92 elantra, and it won't idle smooth, it jumps from regular idle to around 12-1500 and back down, it does this all the time. i have tried a air flow sensor from the junkyard along with an idle switch and a TPS. Nothing has done the trick yet, i have no check engine light on so i don't know that hooking up to a computer will help or not. Any suggestions will be much appreciated, thanks.

 

The good news is that the hmaservice.com website has complete workshop manuals for this model Elantra (J1). The troubleshooting standard is ODB I, which blinks codes that you read with a voltmeter.