[ultraflo]

If you still have your stock distributor, try it out...
Make sure you're not one tooth off or 180 out. It's worth a try before you pull the intake, etc.

Sounds to me like something electrical/ignition related, though I am as baffled as you seem to be. What are you going to do to check the injectors? Have you swapped out the coil with a stocker to see if that make any difference? What about the MAF sensor?

Wish I could be more help!

I apologize for not being "all-knowing"
Just making a suggestion, that's all...