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Bucking on acceleration and stumbling idle at cold start

1999GrandPrix

1999GrandPrix

New member
hey room, i have a 99 pontiac grand prix gt. i just got it back from the shop. replaced the intake gaskets, valve cover gaskets, and oil pan gaskets. also replaced int icm and all 3 coils. now when i accelerate, it starts bucking bad and on a cold start it idles like its gonna die. car has 111000 miles. no lights on at dash. also when i start the car and rev it up, i hear exhaust rattling? any ideas? could it be the cat that is causing this?
 


wires and plugs been bout a year since changed but the fuel filter was changed like 2 months ago. a few months ago the icm went and the car stank like gas comming out the exhaust. could it have fried the cat? no dash lights on though
 
bang on it a little bit with either a hammer or a broom or something and see if it makes noise. what spark plugs and wires did you get? check them anyways.
 
ok found the problem i think. upon looking at the maf sensor i did notice that theer was a crack where i guess a seam was on the top of the sensor. i stuck my finger nail in it and the whole top half of the sensor came off and the gooey stuff inside was there. i closed it back and started engine. upon opening it up a little, i noticed the engine act like it was going to die and upon opening it up all the way the engine did die out. so i just unplugged it and started it up and drove it round a bit until i get the new maf in the mail. so far its not as bad bucking in acceleration. i went ahead and did order an new maf, throttle position sensor, and a new idle air control valve. also going to change the plug wires while im under there. hope this works. havent changed any of the sensors i bought yet so its prolly time. car has 111000 miles on it. hope the hesitation and bucking stops. ill keep u guys updated.
 


alright. bucking is gone. before i changed wires and sensors, i decided to take plugs out and clean them and reset them in the engine. and thats it lol runs like a champ. oh and the sensors will be changed got them in today. hmmm wonder why maf sensor is still good??? it was literally cracked open? anwyaws lemme know what u think
 
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