Engine/Transmission (1994 - 1998) stays in first until 3000rpm

[robertsalverda]

hi guys, i've got a 98 3500, 250,000 miles on a automatic with a sunpro triple plate torque convertor and heavy duty valve body. it's also got one of those b&d things on the side of the transmission but i can't remember what it's called or what it's for ( i'm turning 50 next month, cut me some slack). a couple of days ago the truck started staying in first gear until 3000 rpm( i've got the high rpm springs) then jump into 2nd. the rest of the shifts are smooth. no problem, i thought. just install another tps. it's only the fourth one in 9 years. but that didn't work. now i'm out 130 bucks and no further ahead. any ideas, anyone?