First thing i would check is the gas cap. I would run with it open, it is supposed to be a vented cap i believe. maybe it has failed or is wrong.
Second i would check the air filter for dirt. That got me once, no power in top end at all. Man that air filter was Dirty.
And 3rd i would replace the gas filter if it is more than 6 months old.
86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com
(10 new albums added Sept 16/10)