At wits end, could use some help!
Ok so here's my problem, I have a 02 grand Cherokee h.o.4.7 with about 138,000 miles on it. I had a rough idle issue so I gave it a tune up (changed plugs, fuel/air filter, both upstream o2 sensors, cleaned throttle body , changed IAC and TPS sensors, oil change, pvc valve , fixed vaccum leaks. Took it out for a spin about 35 miles round trip. Mpgs shot up from about 14 to 22 . Going great until I come to a stop , rpms shoot down to about 300 /400 , wants to shut off but corrects itself and fluctuates but stays on. Take it back home and run a diagnostic on it Po175 and po172 and G-switch malfunction. After a few days later jeep dies on me after driving fine . Start it back up and sputters hard and dies, won't start anymore. Anybody have any ideas? Please and thank you in advance