Also check your fuel pressure. If this is not steady under load it'll cause some issues with smooth operation - and it can be difficult to track down until you're left with no other options.
I'll be keen to know what it is so I can keep an eye out for it. I've had an issue before that was resolved with a new knock sensor, temp sensor and a cleaned up TPS (correctly adjusted once installed).
Have you checked your codes yet? Find the two black connectors in the panel above the driver's feet, connect these then turn the ignition to the on position.
Count the long flashes then the short - long flashes are a 10 value, a single flash is a 1 in value. Add these up and it will give you a code. For example three long flashes and 2 short flashes is code 32.
This link should help you work out what your codes are.
And this is what I went through:
http://youtu.be/aLxO4ETlk9c
Cheers
Bennie