[durangeddurango]

just came back from a road trip on vacation, round trip about 1300 miles. when we left trans was fine. about 500 mile into the trip i came off the interstate to refuel, check fluid levels all is ok went to leave the gas station and noticed the trans shifting awfully weird it upshifted 6 times almost felt like i had a shift kit put in. well i continued at highway speeds 75+. and no problems however i did notice that when i was at 90 m.ph. my rpms were at 2300 never have they ever been that low at 90 mph??? any way when i got off the expressway it downshifted normally came to a stoplight now i am in stop and go traffic at 30 mph shifts to second at 35 shift to what i think is 3rd then it shifts at 40 shifts again at 50 all along the rpms continue to lower when i reach 65 rpms were at 2100 which is what is normal it shifts again at 70now my rpm is at 1500. needless to say i had made it home without any problems and the trans is not slipping but i have never seen anything like this before nor has my d ever did this before.still has the problem of6 shifts,no memory codes stored. any ideas??? gas mileage was great almost 38 per gallon so i am not complaning there. my truck is pretty much stock other thanthe exhaust and i had installed a hafc(hydrogen assisted fuel cell which has no bearing on the trans shift points) I will try to duplicate the speeds and graph with the genisis (provided johnny law is not present) but i am at a total loss of what is going on internally to the trans. you just don't gain a extra gear out ofthin air???