at idle my 95 YJ 4.0 will drop down to 400 or 500 rpm then spike up to 1000 or 1200 or so then back down to normal idle range. it will do this almost every 30 sec. and when the vehicle is warmed up and off. when i try to start it again she will not turn over all the way. she will crank and hit the spot where it will normaly turn over but instead she will bog a little and i will have to feather the throttle to get it to turn over and run. i am thinking it is on or more of the following; MAT sensor, CTS, TPS, or the AIS motor on the throttle body. any segetions? I have changed the fuel pressure reg. and i put in a brand new fuel pump and filter. i am almost sure it is a sensor. i want a second opinion.