Ok gents,
here's the backstory. Rebuilt the engine last year. NEw everything. Jeeps been running like a champ for the past year, no issues. Lived in nice warm sunny Florida, used it as my daily driver. Moved to Missouri last week. This morning it was 20 degrees, had to make a 30 mile drive to town for a job interview. Started fine, ran good for about the first 15 or so miles. Then started bucking when under load. Didnt matter which gear. Turned it off for about 30 minutes during the interview. Started up great, went to the gas station got fresh fuel. Ran fine. Plenty of 2.5L power, until I drove it at highway speeds for about 15 miles on the way back home then started bucking again. Anything over about 1/4-1/2 throttle it bucks, and my REM scanner said lean open fault loop on the uphill portions when it bucked... I don't have the exhaust to air box heater hose hooked up... My only idea is the TBI is icing up maybe? Any ideas?
Oh- O2 sensor is doing the flip flop like it should, until I started going up hills then the lean fault kicked in.