Tiburon engine surging

I have a 1999 hyundai tiburon, The engine keeps surging between 1000 to 1800rpm while driving ,it does it interminent times.Then the idle is all over the place, most times it will idle at 800rpm,but at times it just stalls

I have replaced the 02 sensor,Cat ,plugs,Idle air control valve,wires look ok ...could i have a bad coil or a bad ecu?...i havent had the car long.

Sounds like the TPS (Throttle Position Sensor) but I can't say for sure. You also might wnat to check the fuel filter.

I found the problem ,it was the IAT,Intake air temp sensor hooked upside down,.....not enough to light the check engine light.