I have been struggling with a surging idle on my 98 GTP. I have replaced the MAF, IAC, PCV valve, Caniser purge valve, TPS and cleaned the throttle body. I have had occasional codes set for idle higher than expected and Evap system flow during non purge. The only code that still comes back is the idle higher than expected but the idle surges, mainly on cold start until it warms up. If I wing the throttle a little (up to 2K rpm or so, when it comes back down it drops way below the normal 750 rpm and oscillates between near stall and 1300 rpm. Once warmed up a little it smooths out but idles at about 850 rpm in gear and the idle higher than expected code comes back eventually.
Is there actually some kind of idle learn process that I have read about or is that urban myth?
FIXED!!!! New MAF Sensor Was Bad!! See last Post....