Hard shifting after PCM replaced?

[VolcanoVeins]

So I'm a new Vibe owner, and so far I love it ('05 base model with automatic trans., 76,000 odo). This is my first hatchback--which is awesome, as my work requires just this kind of vehicle. After driving a coupe for nearly 10 years, I'm happy to make the transition.

My one concern is that when it shifts from 1st to 2nd gear, the shift is jerky and somewhat violent. This occurs whether I'm flooring it or easing into the gas pedal. I should also note that the Tachometer seems to have a mind of its own, in that it rises and falls completely separate from the behavior of the engine. And the engine light is on.

I realize these are all symptoms of the infamous PCM recall. The thing is, the previous owner took it in for the recall back in '11. I'm just wondering if any of you folks know what might be up with it. The previous owner said that it has been driving like this since he got the PCM replaced, and he just never bothered to look into it. Could it be something else? Is it something serious I need to worry about? Or merely a result from the recall?

I'm gonna take it to autozone or somewhere to have the code read, but I just thought I'd post on here. This community seems pretty fantastic.

[SeattleJeremy]

Welcome to GenVibe!
Are there any noises that go along with this issue? Does it only happen during the 1-2 shift, or does it also happen with the 2-3 shift?
Have you checked the motor mounts?

[lannvouivre]

Check the part/lot numbers on the ECM, it may have been accidentally replaced with a bad one. You can find the numbers on Google, or maybe call your GM dealership and ask for them, or give them the numbers off yours and ask if it's good.