4.1 V6 WILL NOT IDLE

[SS496]

4.1-4 With very mild cam stock heads 8.5cr. Started idling rough and the would not idle normally, 700rpm in gear (200r4)  Idle speed adjusted in helped at first. Slowly got worst. Had to fast idle with throttle.  Replaced carb with fresh one with Cliffs short kit installed.  Started up good on fast
idle then died and has never idled below 1600 since. Vacuum gage showed late timing/vac leak. Replaced dist with swap meet dist. No change. Pulled intake replaced gasket and resealed. Any thoughts?  New fuel filter, have not checked fuel pump pressure. Only working emission stuff is pcv valve and heat riser tube to air cleaner. Engine has 70k on it. 1980 buick century wagon 2.41
diff  normally mpg 16-18 in town 21-25 highway.

[Cliff Ruggles]

Symptoms indicate a BIG vacuum leak.  Secondary throttle plates stuck open slightly?.....Cliff

[SS496]

Did not look at secondary blades, I have shut off all external vaccum, brakes, HVAC, cruise and trans. I'll pull carb and check it out.  I have seen a few pickup coils/pole pieces go bad slowly and was going to replace it tonight as the distrib has about 200k on it.

[SS496]

Triple checked carb, and then replaced pickup coil. Now engine will not start at all, found burned
spot on one of the pickup coil wires. Going to replace coil and module next as there is 12v to dist
and no spark at all.  Thanks Cliff for the input. On to alldata and my old shop books.