Chevrolet Montana Sport Failure

Hello everyone ... I am new and I would like a little help ... I have a Chevrolet Montana Sport 1.8 cc 8v (Chevy Tornado) and for some time it has been pulling a lot, I work uneven in idle, the fault is noticeable with the engine in cold. I had the possibility of changing the coil, spark plugs and IAC valve, the filters are good but still the fault persists, if someone had the same problem I would ask for their cooperation ...! thank you!