Have a '91 Vette L98 6 speed, 80k stock.  Problem is recent within the
last 4 weeks, but is this:  The car runs rich and stalls on occasion.
If I put the AC on the idle will rev up and down a few hundred rpm at
idle and stall occasionally.  After it has stalled, it won't start back
up unless I turn it off for a few minutes.  The car also stalls
intermittently without the AC, so I don't think the AC has anything to
do with it, just that the AC accentuates the problem I'm having.  One
thing I notice if I let off the gas in any gear, the car pulls back on
me and jerks a little bit back and forth... On acceleration the car
seems fine.  I had brought it into a mechanic and the only thing he
could find wrong with it was the throttle body was dirty and never been
cleaned... so he cleaned that and it definitely runs smoother than it
did, but hasn't solved the stalling problem.  He checked the fuel
pressure regulator, cap, rotor, fuel injectors, plugs, etc... computer
shows no error codes.  Any ideas as to where to look would be
appreciated.  Thanks.

Eric