1988 Chevy S-10 Transmission Shifting Problems

Hi, I'm Brian. I recently purchased an '88 4x4 s-10 with the 4.3 v-6 and the automatic tranny is experiencing a shifting problem. It starts up no problem and it seems to idle ok, but while driving, especially under heavy acceleration, it seems to rev real high before shifting, and sometimes it doesn't shift at all. When it shifts, there's no kick or anything which indicates to me the transmission is good. I have the Chilton's manual which talks about a "Transmission Converter Clutch(TCC) System", which is controlled by the Engine Control Module(ECM) via a solenoid which is mounted on the outdrive housing of the tranny. This TCC checks engine speed and then allows the torque converter to couple the engine to the tranny. So I'm hoping that you could suggest to me if you think what I've described sounds like it is this solenoid that needs replacing, and if so, how difficult is it to get to this solenoid, or if maybe the torque converter itself might be the culprit. Or if maybe it's something else altogether. I greatly appreciate your assistance with this, and by the way, this website is AWESOME. Thanks again for any help you can give.