I have a 99 Pontiac Trans Am LS1 its got about 140,000 miles on it and recently its started running shitty. I does this weird like hiccup sputter thing but only when i hit between 45 and 60 mph. The service engine soon light came on and gave me emissions codes, the first one was my EGR valve which i bought new and replaced, still nothing. Then it gave me the code for my Catalytic converters which i have known about. i would think if that was my issue, it would do that all the time and just run crappy in general.. I also recently did a tune up, plugs, wires, the whole nine.. And still nothing. I was thinking possibly injectors? Seafoam also did nothing for it. Does anyone have any ideas on what to do or what to try? Any help would be awesome. Thanks.

 

Dirty fuel filter, dirty fuel injector(s), leaky fuel injector. These can cause wierd running issues like that.

Maybe put a full can of SeaFoam into 1/4 tank of gas.....when that gas is run out, change the fuel filter.

But if the CAT is going bad....thats the problem.

And don't put SeaFoam into the top end anymore. Its dangerous and it cleans almost nothing. Use MCCC to clean the top end of an engine.

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Check your plugs and wires to make sure one hasn't popped off. If you recently changed them it's a possibility.

 

What are the exact codes you were getting? I'm wondering if you may just have a dirty MAF.

 

i need help for one i am trying to figure out how to post a thread and second i am having the same trouble you are with your ta i have replaced the spark plugs wires o2s all 4 and majority of the gaskets can i get some help i have headers intake exhaust i cleaned the maf sensor no i did not break any of the little resistors still i have a sputter new clutch flywheel master and slave cyl fuel filter new the car says its running lean its driving me and my mechanic crazy we can not figure it out i have been reading alot of these post and this is crazy

 

i need help for one i am trying to figure out how to post a thread and second i am having the same trouble you are with your ta i have replaced the spark plugs wires o2s all 4 and majority of the gaskets can i get some help i have headers intake exhaust i cleaned the maf sensor no i did not break any of the little resistors still i have a sputter new clutch flywheel master and slave cyl fuel filter new the car says its running lean its driving me and my mechanic crazy we can not figure it out i have been reading alot of these post and this is crazy also i am not sure how to keep track of this post so please send me emails or something

 

Mine is doing this same thing. We changed vacuum line to the air canister, spark plugs and wires, fuel filter, new head and intake manifold gaskets, mass air flow sensor, rear main seal (had an oil leak), header gaskets, radiator, all in the last year trying to figure this out. Did you ever find out what it was?