What are symptoms of bad TFI module?

[PKRWUD]

Well, it's not a lean condition, because the engine would have stalled when you removed the vacuum cap. I doubt it's a rich condition because you would smell it, and have smoke. Since the TFI helped some, I suspect it's an ignition problem, possibly the coil. If you have access to another coil that you know is good, try it and see if things improve.

Have you cleaned the IAB or adjusted the TPS recently? If you have, and didn't reset the ECM afterwards, that may be pert of the problem as well.

Try a friends coil.

Take care,
~Chris