600 cfm electric choke 1406 carbs are set up for "economy" out of the box......which means they run pretty lean (DANGEROUSLY LEAN) other can explain what that does in detail but essentially it detonates pistons ( UN-GOOD)
Move the stock front jets (95-98's I think) to the rear and put the 100's in the front with the stock meter rods...... replace the stock metering springs with the Orange ones from the kit....
remove the vacuum advance tube and plug the port at the carb........ then start dialing in your timing
OH ya moving the accelerator pump UP to the TOP most hole will give you a lil extra squirt
The counter weights on the secondary s are cast/stamped....you can shave them if you want/need to for quicker open but do it a very little bit at a time...once you go to far you are screwed.....shave a taste then try it......shave a taste then try it when you get close STOP.....typically the next shave will take you over the edge and it will open too fast and bog....
ALSO check your ignition....sounds a lil like you may be getting random spark levels..... are you running points or HEI........if points they may need replacing....if HEI have it checked....it may be failing or going "random"....
my 2 cents
good luck