What cam are you running, specs? Have you swapped distributors to make sure it is working properly? You can run a test to check the O2;s so you can try to eliminate them from the equation. I'll have to check my book at home on how to run that, and I'll post later.
I know with my last cam, it ran pig rich at idle but it need the fuel (aggressive cam) or it ran lean as can be at the top end. The exhaust would burn your eyes it was so rich, but it didn't have any hesitations and ran good.
------------------
Check Out My Site 91GT,Holley SysteMAX II Kit-Heads 2.02" x 1.60" port matched to a 1262,Anderson N-61,24#,76mm C&L,Full MAC exhaust 1-5/8" Long tubes,2-1/2" O.R H-Pipe,2 1/2" cat back, No A/C or PS or emissions, 12" K&N Filter,RNH PERFORMANCE Ram Air,Ron Davis Radiator,Full Suspension,S&W 8pt "X" brace,JAZ seats,3:73's,Welds..etc,4:30's and 31 splines coming very soon!