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01' grand prix stumbling

00superduty

New member
Ok i'm new and i wish i'd found this site three weeks ago. I'm bill and i used to post alot on diesel sites because thats what i got. a 2000 power stroke. so any way my girl friend has an '01 grand prix. she was coming home a few weeks ago and the way she comes has a lot of hill's and a few that are pretty steep. she calls me and says the car won't down shift and it's getting hot going up the steep hill. she made it home and tells me now it has no power and it jerks and stumbles real bad. i start checking it out. no codes. i check farther and found a broken front sway bar. thats it. i replaced that and drove it my self and it reved real high (4g) and would'nt shift. i got a code that time. po300 random multiple cylinder misfire. replaced plugs with plain ones. i know thats a no no but then i got a po305 misfire cylinder 5. so, i put new iridium plugs and autolite pro wires. still stumbles and jerks but no misfire but a po404 egr something. i cleared it. it came back with a po401 & 403 i think. so with some advice i put a new egr valve on. no codes thrown but a pending code, po 404. what else could this be? it stopped jerking and stumbling for the most part (very faint if at all) after a few miles of hard to moderate driving but now it runs around 230*F if i get on hard and i'm affraid its going to get hot on her on her way to work. any idea's? sorry it's long.
 


Get a new 180* Thermostat and have the system flushed to get rid of all of tha Dexcrap in the system...btw what motor? 3800? 3100? Might try pulling off the coil packs too and cleaning the terminals and ICM (aluminum part the coils sit on) might help you a bit more too. I'd say getting the system flushed should help you out, especially putting in that lower tmp T-Stat to keep things cooler.
 
it's a 3800 series II. i took it to the dealer and their saying the cats plugging up. it's not too bad right now but it will quit running sooner or later. the thing that's bothering me is i stopped in yesterday and was talking to one tech and he was thinking mabe a maf sensor or something along that line telling the egr valve to stay open. now a diffrent tech today says plugged cat. i hate to spend 750 bucks on this when the second tech got it wrong and it's just a sensor. i do need to have the radiator flushed. as far as i know it's never been done. and its got 165k miles on it. it does have a new thermostat in. last year i think.
 
Too bad it has over 120,000 miles on it. I had similar symptoms and just had my plugged cat changed last week at the dealer for free. My 01 GT has 113k.
 
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