Help. surging from 800-1200 rpm

Ill give you a bump
welcome to :SNSign:
come on guru's help the new guy out....

Welcome!

Any codes?

Does this seem to be an issue with the engine management hiccuping, or with trans calibration shudder (it sounds like you have an AODE)?

Do you still have the EGR physically in the car? If not, was it's function turned off in the computer?

Tune up parts are relatively new? Take a good look at your plug wires - inspect each inch of each one. And/or look for a light show at night (misted water sometimes helps create said show).

Provide as much info as you can - little things the car does, etc, because there is a sink full of things that can cause issues like that.

Good luck.