87 350 TBI timing troubles

[Suprzuk]

Just got everything back together from replacing the intake gaskets. Truck fired right off the other night. I got to timing it last night. I disconnected the wire that I think is the advance coming from the ECM......(the wire looped out of the wire loom and back in below the brake booster). If I try to get the mark on the balancer down in front of the timing plate it will stall the truck out. If I leave the mark about 1/4" CCW of the plate the truck runs great.

What could be causing this? Did I not disconnect the correct wire? Am I off a tooth on the dist gear? TIA for any help.

Kevin