Codes for tourque conv.?

97 regal GS...165,000 miles. Tranny rebuilt at 110,000. Car is bucking. mostly in lockup. Now shifting is hard and bangs alot...was driving about 15 mph and it was staying in the wrong gear...rpm's were too low and had no pickup...my guess is that when tranny was done they may have not replaced tourqe conv...when all this crap w/ the banging and stuff the SES came on..is there a code that will point tothetourqe conv. if this is the problem? If so would it be reasonable to drop the tranny to just put a tourque conv in? one tranny shop didnt want to guess what the problem was and wanted to rebuild the unit...i cant afford that kind of $ now. And a rebuilt tranny would = or be greater than the book value of the car.....

Best thing to do is pull the code (DTC) to see why the SES light is coming on.

The hard shifting could be a line pressure/PCS issue.