Pinto not running right.....

hey guys hoping you can help as I'm sure I'm missing something simple. Can't get the escort running right at the moment. Bottom end standard (very tired) head heavily skimmed, big valve, mild cam, adjustable cam gear. 45 webers, standard Sierra electronic ignition.
Problem is car is hesitating both under load and highway cruising. When it does, tacho jumps around. Have tried changing plugs, leads, dizzy cap, dizzy, coil. Have yet to try different ignition module. Is this an ignition problem, timing, cam timing or fueling? Issue?
Any help greatly appreciated.
Thanks.

Thanks, will give it a try.

Erratic tacho can send you down the wrong track, espicaily when ther are about to die.
Sounds like a possible air stall, thinking 45s, big cam, high vacuum low flow, then butterfly's open!!
Check no leaks on inlet manifold or piping,(carbs usually spit alot)
Check if all accel pumps working in carbs.
If you are going to change cam timing, take note of the orignal setting so as you can go back to it.
Try setting it to equal lift on overlap as a starting point, and check piston clearence to valves each time you change the cam setting before starting engine by turning it over by hand for two revolutions, just in case.