Hi,
Well, I have the exact same problem as you do with my car and I think the answer has been found. There were no vacume leaks, there was good fuel pressure, fule system had been flushed, everything fine (head job 200 miles ago)...it turns out that the distributor cap has a broken part in it...it is a little black nipple in the middle of the inside that is suppossed to contact something, but isn't doinf a very good job right now...the reason for the intermittent hesitation. Might want to take a look at yours...remember I had the exact symptoms you described, so there is a good chance your problem lies in the same area.

Mike

Ps - I get the car back tomorrow afternoon, so I'll let you know for sure.