what im saying is under normal driving not hard acceleration just normal easy driving those are the shift speeds all the time. no the big tires didnt start this i had the tires on for a cpl yrs. then trans went bad had it rebuilt and then it does this. if i keep it above 45 like say 50 it will stay in overdrive. if i cruise at 45 or so it will drop down and then back up down and up down and up etc. around town at slow speeds no problems unless i cruise at 35 or so and then it does the same thing. but if i go 40 and switch od off its fine, i heard that when u have a e40d rebuilt with upgrades u should upgrade your pcm to at 1994 year. any one know about this? says if u dont it could cause shift issues also. any help on wich pcm i need to get? it didnt do this with old transmission so maybe i do need to upgrade pcm. any ideas guys?