I have a 2008 Grand Prix GXP currently at 155,000 miles . I had my transmission rebuilt around a year ago. To make this short, they did a job. They actually did more than just a bad job, I'll go ahead and call it TERRIBLE. They also replaced my computer. I kept getting my Check Engine light but they would "fix" these issues. I had the speed sensor being bad one of those times and they supposedly replaced it. Anyways, I finally had to go somewhere else and pay someone else to clean up their mess. In this year, I've fixed the transmission leak they caused and could never fix, replaced the speed sensor with a new one (since they apparently NEVER replaced my speed sensor according to the new shop) and I actually had it go out on me while driving and start giving me random speeds and messing with my transmission shifts, had my transmission computer replaced, and had to have it reprogrammed.

So here we go, now, I am getting a P0700, P0716, and P0717 including weird shifts. I have also noticed that when it rains (i do not think it is my imagination) my car shifts even weirder. The shop I have been going to and has been helping me out a lot looks at me pretty weird when I tell them that. The weird thing is does is that if I have it at 2,500 rpms if I push it to get to 3,000 rpms it finally shifts or the tcc lock up kicks in(????) not sure, but is pretty hard of a jump and I have it on video but basically just looks like it finally gets to 3,000 rpms and drops down to 1,500 rpms. It's usually when i'm going a little faster (60-70mph). And, I actually do not let it reach 3,000 rpms but I let go down to 1,500 rpms and I press the gas a little, it jumps up easily to 2,500 like it's loose. I'm not great at explaining.

Sometimes, it feels like I'm pushing the gas way too hard and my car is not accelerating because it will not shift. There is all types of problems but those are the only lights I get. No issues with my speed not displaying. I also am getting a P0300 (not on Autozone's computer check) but on the mechanic's. He's tried looking and my check engine light goes away before he gets to it. It always comes for 2 or 3 days and then goes away on its own and he tells me he can't do anything really without the light being on so I haven't been able to drop it off for too long.

Anyone have any idea what could be causing this? I have put so much money into my car trying to fix the tranny issues and I am getting so tired of it. Any ideas are appreciated!