This sounds alot like the set-up I was experiencing w/ my freshly rebuild 350ci @ 160K. After we finally got it back on the road. Minus the part of all the parts being in real bad shape. Come to find out, just like you discovered, the timing was advance to like 10* adv. Once we un-plugged the 'puter connection, to re-set the timing back to zero, the hesitation and stumblin/surgin stopped.
Could the timing chain poss. be in as bad a shape as the other parts you've found???
Silver '02 35th Ann'y A4 Camaro Z28 w/ T-Tops and 16" chorme w/ BFG g-Force T/A KDWS 245-50/16's
Whisper Lid & MAF, AC Delco Iridium(pt# 41-985) w/ Taylor 8mm plug wires, Zaino and tint