Studder question Please look

O.k. here goes:

My car a 98 Z24 cavalier 5 speed, has a studder in it when you take off. It dosen't happen when I'm turning the car around to leave the driveway, but when I leaving my driveway and getting up to speed. It only happens after it's been parked. It dosen't matter if the engine's cold or hot. I have noticed if you let the car run for about 2-3 minutes after you crank it, it will NOT studder at all when taking off. The car never dies when this happens, but acts as if it's flooding. When this happens if I mash the clutch in the RPM's rise and fall between 1300-500 a couple of times then returns to the normal 900-950 RPM range. This is the only sign the car gives to any trouble, the rest of the time it runs perfect. I have changed the throttle position sensor, fuel filter, plugs, and ignition packs in an attempt to help this problem. The car has about 110,000 miles on it, have always ran Mobil 1 5w-30 full synthetic motor oil. Yes the car has been ran pretty hard on occasion, nothing over the top though and has quite a list of upgrades, mostly external and bolt-ons. So any ideas would be wonderful. Thanks in advance. Sorry for long post.

Ok I'm confussed. So it studders but if you hammer the gas then the RPM's go up but the speed doesn't? Is it like a clutch slippin

Ok I'm confussed. So it studders but if you hammer the gas then the RPM's go up but the speed doesn't? Is it like a clutch slippin


No, it's not a clutch slipping. It only happens when I'm going like around 5-10 mph. The harder I press the gas the more it feels like it's flooding, kind of a held back feeling. When it happens if I mash the clutch in the rpm's jump around a few times then it clears out. It dosn't do this any other time while driving, just when your taking off and getting up to speed. Like I said it dosn't do it if I let the car run for a few minutes, just if I take off right after cranking it. I'm not taking off fast either, just a slow, steady accelertion. Thanks for the reply though, and any ideas are welcome. I'll also try to respond to any questions someone may have in trying to help me on this. Thanks

and no check engine codes? Hmm have your tried some systme cleaner? Might be some injectors, thats always a possibility. Also how old is the O2 sensor

Sometimes an IAC(idle air control) motor can stick and cause an almost suffocating effect causing the engine to run lean for a period of time. I don't wanna tell you to replace it, not my place to say, but if you're somewht familier with it, it might not be a bad idea to remove it and clean it, first with brake clean then some lube such as WD-40/ PB blaster.

Thanks so much to everyone who replyed. I'll try to answer all the responses. The car is throwing NO check engine lights, not even a flash of a warning light nothing. The O2 sensor is as far as I know stock, I belive all of the sensors are original, except the TPS. I have ran Sea-Foam through the fuel system, I even took Sea-Foam Deep Creep (Spray type) cleaner and cleaned the throttle body really good. I try to take a look into the IAC motor and the injectors next. Thanks to everyone who responded. I guess all that's left is to try everything step by step. Thanks again.