I have a Proform 750 Race Series carb that's decided to drive me nuts. After changing metering block and float bowl gaskets, I cannot get it to draw fuel through the idle circuits. The lowest I can get it to idle down to is 1400-1500 rpm. This was after switching back to the original gaskets. They weren't bad. I had simply done enough jet changes, I felt fresh gaskets wouldn't hurt. Timing is bang on, at 36 total. I have blown out every air bleed and fuel passage in the base and metering blocks, set the throttle blades at the proper initial setting. The idle, as it is, is fairly rich, but that's the only way I can get it to "idle" at all. Below the 1400-1500 threshold, the only way to keep it running is to jiggle the throttle enough to spill some fuel from the accel pumps, but then it will simply run out of fuel after a few seconds. ?????