2000 Jeep XJ Sport (for further detail)..
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Howdy! Been awhile since I last posted a thread. So recently I've been having surges in idling when cruising around 55mph. Its whenever I let off the gas, and that's the other thing,
fuel economy has been kicking my butt. Paying $5 to go 15 miles. I've read that the idle surging symptoms are most likely due to a bad Throttle Position Sensor (TPS), its a very easy
replacement and it ain't too expensive. But the fuel economy on the other hand can be a thousand other things.. Right now its just hurting the ole pocket book, and I just want to make
sure I have an idea of what maybe causing these issues. Thanks for checkin in!

 

Being that you have an OBD2 system, it might be worthwhile to get one of the engine management app setups so you can see what's going on. Jordan96xj has several posts where he recommends one of the particular brands and with all the live data I'm sure you could get some good advice on the MPG issue. If you haven't done O2 sensors in a while it might be time to invest in some new NTK brand sensors simply as a maintenance replacement.

 

Maybe you can check Fuel Pulsation Damper (in fuel rail) first. I Have experienced bad fuel economy because of that.