both some sweet rides man!!
i have been through the stupid po742 code.... there is a solenoid behind the side cover in your transmission, well.. actually there are lots of them, lol.. the one you are having the problem with is the torque converter clutch solenoid (tcc), it's probably all gunked up inside so it isn't letting the torque converter do its thing.
here's a writeup i used to fix the solenoid.. GM 4T65E solenoid shift valve replacement TCC/PWM EPC 1-2 2-3
and here's a diagram showing which solenoid i am talking about..
also, i have a 97 regal with only 100k on it, trans and motor is mine and the front seats are taken, but i have multiple parts left and the whole body in fair shape if you ever need anything!
