Ok, someone PLEASE tell me I'm on the right track here.

I played with the IAC passages (copper tube mod on the BBK 58mm) and the throttle stop.

Fired her up cold, went through the setting routine a couple of times, got the idle set almost dead on and the IAC at 41, and my map was hovering right about 15.0 in hg at idle.

THEN!!!! (there's always a then), I watch it. Map starts coming up to about 17.5-18.5, IAC gradually closed to 0, and idle took a move up to about 1100 from 800, , O2 mV started to move up from 450 to about 650+, all in open loop while the car started to warm up, all the indications of the problems I've been having.

Could an external/internal vacuum leak cause this????? I think large vacuum leak because as the car warms up, things expand. As they expand, a gap may form. A possible large vacuum leak behind the TB somewhere, letting enough air into the system to drive the IAC shut, raise the idle, and cause the computer to dump a bunch of extra un-needed gas in, giving me my extremely rich problem.

If this is the case, I think it may be on the left side somewhere, this is why: I played with the tune and drastically raised the injector constants. The left side stayed bottomed at 108 while the right was split and up in the 1-teens. With the regular tune, they're both dead at 108.

Feasible??

 

I don't claim to know anything but wouldn't the vacuum level of the MAP go down if a leak were getting greater? I think the IAC numbers would go up too.
Is the majority of your problem that the idle is high? Does it stay high or come down and go back up?

 

The idle is the last thing I'm trying to worry about. it's the loading up on fuel that's causing the driveability issues. I took the car down to FBC in Baltimore today and dropped it off, and I noticed quite a bit of surging at a steady speed in all gears.

As for the vacuum leak, basically with air coming behind the metering system (IAC, TB, TPS, MAP) it's going to cause the idle to come up, in turn the computer will shut the IAC to try to maintain the target idle RPM, which it couldn't do.

My main question now is if a vacuum leak of the magnitude to cause a shut IAC and still idle the car at about 200+ more than the target would also cause a load up of fuel into the system.

FBC will get going on it early next week, so hopefully I'll know something soon. They're going to put it on the WB to start with.

 

a while back I was having a problem with my car running sooooooo rich. you could smell the unburned fuel. turns out the last bolt on the exhaust manifold was broken. there was no way to tell, until I pulled them off when i went to LTs. The gasket was shot. After I put the LTs on, overly rich problem went away.

 

My initial reaction to one bank being overly rich, and the other looking good would mean that the vaccum leak (if there is one) would be on the side that WASN'T running rich. The computer might see a slight lean condition on one side, and compensate as a whole, thus dumping fuel to compensate.