Ok, well I think we FINALLY figured out what was causing the problem!!!
After all this work on everything else, it turns out the problem was something to do with a GROUND!
My bro was working on it last night, and he replaced the fuel filter. He took it for a ride and he called me to let me know he thought it was gone, then sure enough he called back and said it was happening again.
At this point, we figured it could be the TPS, so he checked it then disconnected it to see if there was a difference. The car ran with it off, but the problem surfaced again. Some more pondering under the hood, and he called and I mentioned someone online had a problem with a ground "heating" up to the point it was losing good contact.
So, he had a friend start it up and noticed a small spark near the battery ground. (this was at night) He moved the wires and found a ground that was apparently loose, which was causing the tach to jump around. he tightened it, then took it for a drive, and it was gone.
he's gonna double check it today, but I hope to GOD it's gone, cause it was starting to annoy the SHI* outta me.

It's funny because I thought it could be a ground problem, but I could never find out where it was. Well, he fixed it and I'm gonna take him out to the bar for a celebration of sorts.

Thanks again for all the help/suggestions on this topic, I guess the only good thing about it is now I am an expert on this issue, LOL.

 

I should have said that...same shit happened on my old roommate's GSR swap.

 

Well,
I tested it this weekend and the problem is GONE!!
Thank God, it was really getting on my nerves...

Thanks again for the help guys!

Later