transmission problems after gears installed

[chiaronate]

i have a 1994 mustang gt with automatic transmission. i've recently had 3.73's installed in place of 2.73's and am very happy with the improved acceleration. however, if i hit the gas enough (probably 1/3) the transmission slips out of gear until i let off the gas and the rpm's decrease. it then goes back into gear. i had my transmission rebuilt approximately 15,000 miles ago, and it didn't slip with the 2.73's that were in it. i read a post on here that there was an article in a hot rod magazine that said if more than 3.55's are used in a 1996-1998 mustang, the line pressure may get too high and cause it to slip. any thoughts on what could be causing this? are 3.73's too much without a computer chip?