Trouble with my 2004 aveo hatch :(

[Tr15hyp4nt5]

I recently purchased my car and immediately ended up replacing the water pump, and front control arm. Now ill be the first to admit i really don't know much about cars. BUT i was told to get my oil changed and i did. Well i got it back and as i was driving home it started to studder and less then a mile later the check engine light came on. i pulled over. Check my fluids. Now i ended up putting transmission fluid in because it was a little low. I ended up leaving where i was and the car continued to studder bad when shifting. then continued to studder at higher speeds (over 45) i was advised not to drive to fast in fear of breaking something. once i added the fluid it decreased the amount of studder. i let my car sit for two days. once i drove it again it was fine for an hour drive (to work and back altogether) the engine light had gone off and the studder subsided. Now the next day i get in it and the studder is back. But only at around 60mph. Just trying to figure out what could be going wrong. its had a hard idle since i bought the car. But its starting to shake alot more. I do not know what maintenance has been done. :/. i know the radiator was replaced along with a rebuilt engine (caused by a broken timing belt) i bought it with 18k miles on it. (the engine) the rest had 100k and im around 104k. any ideas would be appreciated. i was told to get a transmission service done hoping it helps.

ty

[avguy]

The first thing to do is go to a parts store (Autozone, etc) that reads codes for free and find out what the codes are. I'm guessing that one of them will be a P03XX, which would explain what you're describing. One thing that's not a good sign is a new WP on an 18K rebuilt engine. The WP and other timing belt components should have been replaced as a part of the rebuild, so this repair does not bode well. You should check the documentation for the rebuilt engine to see what, if any, warranty came with it.

[Tr15hyp4nt5]

ill deffinatly be going to autozone this evening when i get off work. ty. ima check the documentation to see whats up. ill be back with more info. thanks for ur help.

[Tr15hyp4nt5]

Got the codes. 1791, 122 throttle, 700. Transmisson. :/

[Tr15hyp4nt5]

She is out of the shop. Only $150 later. New throttle postion sensor. thank goodness. But thats what was causing the studder. Before I took it in the shop when I would start it it would rev really high and stick for a few seconds. So glad he figured it out. Other codes disappeared aftervhe fixed it too. So happy to have found the problem. Ty guys!

[Tr15hyp4nt5]

codes are back -___- wiring harness now. one thing at a time i guess.

[avguy]

codes are back -___- wiring harness now. one thing at a time i guess.

Are you saying the P1791, p0122, and p0700 are all back now? What does "wiring harness now" mean? How is it running?

[Tr15hyp4nt5]

Are you saying the P1791, p0122, and p0700 are all back now? What does "wiring harness now" mean? How is it running?

Ill know tomo what codes came back. But yes my machanic says there are still codes on it. He said that there is some bad wiring. Shorted wires, wires that are spilt and coming partially disconnected. im not completely sure I was told my wiring harness is a mess. ill know by tuesday and update. But its running better .its almost like its losing power at times. not cutting out completely but bogging down. ive drove it three times since the light came on. Its still