A vacuum advance hose AIN'T going to cause 2% of the problems you've detailed. Plus it off, rip it loose, no way José.
You've apparently been dealing with idiots masquerading as professionals.
This is what you need to do with an older Bounder or any other engine.
FIND A SHOP THAT HAS AND KNOWS HOW TO USE
A Cylinder-Leak down tester. ALL EIGHT CYLINDERS need to have a leak down test performed.
Perform an exhaust gas SMOG TEST with certification needed. This test is much cheaper. Use a TEST ONLY station.
When someone tunes up an engine that has a distributor with mechanical and vacuum advance mechanisms they use an ADVANCE TESTING TIMING LIGHT and an ENGINE TACHOMETER to VERIFY the advance curves in the distributor are not out of whack. They are usually ridiculously broken.
ROCHESTER QUADRAJET CARBURETORS are notorious for floats that absorb gasoline, get heavier, sink, raise float levels, and engine runs rich as hell. Also these carburetors wear out the steel throttle shaft hole in the aluminum carburetor base. To check, CAREFULLY squirt WD-40 around the shafts when the engine is at idle. The faintest stumble or RPM change and you have a mileage killing leak.
Your rig is probably so far out of whack as I write this, it isn't funny,
