Volkswagen Repair: 69 VW bug, intake leak, flamable

Question
I've been driving my 69 since it was new (a record?); done most of the tuneups, etc.  Seem to have a recurring problem for as long as I can remember with idle/missing; doing it again.  It has larger heads, 90mm I believe, and a Holly Bug-spray 2 bbl progressive.  I adjusted the valves (they were tight), set points-timing, adjusted plugs (had large gap).  Ran a bit better, but still poorly.  If I pull off plug wires 1 or 2, makes little or no difference in idle.  I found out it idles almost the same with both 1 and 2 disconnected, although I'm getting a good spark at the distributor. (Take off 3 or 4 and I get a good drop in idle.)  I have sprayed a rust cleaner (flamable) on the rubber that clamps the intake manifold to the carb; also around the heads-Carb.  Could not distinguish any increase in idle.  BTW, my bug has no choke; have to feather the gas pedal for a few minutes till warm.  I can cruise down the highway at 75, no problem, but  backfires when slowing down.  I'm thinking I must have an intake leak, but unable to pinpoint it.    Could the fuel filter cause this?  How about the float?  It amazes me that the car will run on two cyclinders!  If you need more info please let me know as I'm aware that I'm looking for trouble if I don't solve this (I must drive the car 8 miles to work, and back).  Thanks for your help, Doug  

Answer
Doug,
You've owned that car since '69?? That may be a record! You must live some place hot and dry to be able to keep the pans and rockers from falling apart!
On this motor, did you ever check the compression? I usually start there just to make sure I have something to work with. If the comp. checks out, go back to chasing an intake leak or carb problem. Does this thing have dual port heads? I've seen those end castings warp from the heat but not show up when sprayed with carb cleaner. I usually file the castings with a large flat file and use the thick paper int. gaskets, if available. Is the carb a Bug Spray or a progressive? Two different carbs with different intake center sections. Most Bug Sprays use the isolated runner type (separate tube for each bank of cyls) while most progressives use the plenum chamber manifold (all cylinders pull from one area). If it is a Bug Spray, with the isolated runner man., I'd guess you have a clogged idle circuit on the 1 and 2 cylinder side. That would explain how it runs 75 or 80 out on the road. Try bringing the rpm up to about 1800 or so and pull those 1 & 2 wires off. Does the rpm drop? Let me know!