i have a 98 ram 1500 2w drive with auto transmission. when im starting off in the truck sometimes not always the truck will not shift out of 1st untill i mash the gas then it seems to shift and to go along with this also sometimes it will decide to downshift hard and actually slow the truck down like i was driving a 5 speed! what could cause this plz any info would be great!!

 

I'd start off by checking the tranny fluid. make sure it's at the proper level and NOT burnt. then move on to the Throttle valve and make sure that it's where it should be (adjustment wise).