The car used periodically pop out of the intake manifold if i drove it without warming it up. Now it starting to do it when the car is warmed as well. It does it every once in a while like ill be driving at part throttle and it stutters, then itll buck and slightly pop outa the intake and the run fine again. What gives? I JUST replaced the 02 sensors this morning, cleared all the codes, took it for a drive, drove fine for a couple of hours. Then after a few errand runs it did the same thing. Get home only get one code now. Code 91 with KOER, no codes with KOEO (just the 111). The car is on 93 octane, timing at 12-13 w/ spout out. Just replaced IAC (new gasket as well). 4 month old plugs & wires. Idle surges like crazy after IAC replacement. Used to idle at like 500-600 (thats how i knew IAC was bad), after i replaced it idles at a steady 800, but when i go into neutral coasting to a light it sticks at 1300, then comes down to 900 and then goes up to 1000 then back down etc. etc. What do you guys think it is? Maybe fuel pressure reg is going bad?