New here and tried searching but came up with nothing similar. My 06 LJ 4.0 (155000 miles) recently developed a habit of going to a fast idle/high rev of around 1500 RPM's or so. If I blip the throttle it settles down until you take of again and it repeats. I installed a Genright 31.5 gallon fuel tank and replaced the fuel pump assembly at the same time because it was a whole lot easier and I didn't want to drop the new tank anytime soon. I had a code for EVAP system small leak which I attributed to the vent hose from the tank to the filler neck as the hose that came with the tank was rather short and had no clamps. I installed it and put some zip ties on it until I could get a new section of line and clamp, which I did a week or so later. I also had a code for O2 sensor which I forgot to write down but it was present long before these symptoms began. I have searched for vacuum leaks but it's possible I might have missed one. Anyone have thoughts on this?