04 jeep wrangler 4.0 engine auto trans, hesitates after driving 50-60 miles at traffic lights.

This sounds like multiple things. You do have a vacuum leak, it also sounds like the EGR valve is stuck. There is no reason to be replacing thermostats that often.

My used 97 jeep wrangler fuel / economy problems: My vacuum canister was completely full with crud (replace). also my coolant temp sensor was bad (twice replaced), effects fuel mixture. and O2 sensors were bad (effect fuel mixture) due to being fouled by spraying too much oil on spector air filter (now wipe off excess and let dry in sun), also carb cleaner appeared to foul O2 sensors (stopped using). Also sensor input/output signals were constantly being interrupted by battery sliding into computer harness, which I cured by placing a 1" spacer on rear battery clamp to push battery away from computer. After curing these problems my fuel economy went from 55-60 miles per 1/4 tank to 75-80+ miles per 1/4 tank.

Unless you have a flushing machine you will not be able to empty the torque converter.If you have a 3 speed auto you are looking at 9 quarts total.If you have a 4 speed transmission you are looking at 10 half total.Be sure you check the fluid in neutral and not park.

Did you check your ATF level? I have an ATF leak somewhere and when my ATF gets really low my auto trans will keep slipping out of gear until I dump another quart or two of ATF fluid into the trans.

quite possibly it may be taking a little while to build fuel pressure. next time try cycling the key on and off 3 or 4 times with out cranking the vehicle to allow the pump to build pressure the try to star it up if it starts right up then your problem is it's just taking time to build pressure

hi,

sounds like a vacuum leak, injectors clogged, bad plugs, plug wires or maybe low tranny fluid or combo one all, have it dynoed to save yourself some money of course.

good luck

J

does it have a vacuum controlled fuel pressure regulator, if so check it for leaks into the intake. Also check fuel pressure

Your vehicle’s computer system has self-testing capability. When the computer senses that there is a problem with some of the components it stores the correspondent trouble code(s) in its memory and lights up the "Check Engine" or "Service Engine Soon" light to tell you that there is a problem and you will need to have the car diagnosed and repaired. The only thing you could do is check the gas cap to make sure it's tight. A loose cap causes a fuel vapor leak and that will turn the light on. If the cap was loose it may go off after a few drive cycles, if not you will have to have it checked.

what fluid is the trans line filled with?

shift tranny from 1st-3rd if engine revs up clutch needs replacing