Hesitation at cruising speed!

[hillbilly*tj]

I recently bought a 01 TJ 4.0/5spd with only 59,000 miles. The other day when I started it, it started fine but immediately started idling EXTREMELY rough and the check gauges light came on. It wouldn't take gas but after a few minutes it settled down and ran normal but no SES codes ever came on. Now when cruising at 65 mph it seems to be real sluggish. It doesn't loose speed but it won't gain either. I bought it with 35's and 3.90 gears and the exhaust stops just past the cat. I've changed the air filter because that's what it acted like but that only slightly helped. I've been goin through the forum's tryin to find if someone else has had similar issues. Any help would be much appreciated!

 

[jeepjeep!]

If you have a local quick lube around ask if they have a fuel injection service. . Im a manager at a service center in my hometown and we offer an FIS for 34.99. .most are three step process. Fuel tank treatment. Removal of air filter duct work and manually cleaning the throttle body with a foam intake cleaner and lastly a fuel injector cleaner that we hook usually through a pcv valve or brake booster to be vacuumed into the engine. . I do alot of these on the 4.0 including mine. Once a year, And I always run lucas fuel treatment or something like seafoam every few fuel stops. . Also you may consider basic tune up stuff as a starting point. The reason I do this service on alot of jeeps is because they are jeeps and are in dusty offroad conditions more often. .its a considerably low cost service that more times than not greatly affects the fuel economy throttle response and overall life of the engine.