Well, I wouldn't call it a "problem" really; it'* what we in Tech Support call a "WAD" (Works as Designed).

47-48mph is the minimum point where the ECM allows the Torque Converter Clutch solenoid to lock the engine to the final drive and bypass the transmission'* torque convertor, which eliminates the normal slight slippage of the convertor and locks the engine directly to the drivetrain. (This is why, when the TCC solenoid gets stuck, the engine stalls when you come to a stop at the end of the expressway exit ramp or a stop sign, but restarts immediately when you put it in Park or Neutral.)

After lockup occurs, your RPMs will drop way down, so getting on the gas at that instant might feel kind of boggy as the ECM tries to decide whether to kick down out of lockup or just accelerate through it. Load factors determine what it should do -- gas pedal position, manifold vacuum (how much load the engine'* already got -- uphill, heavy load, etc.) -- and it'll either kick down for fast acceleration, or hold in lockup and look for boost from the supercharger.

I remember once on vacation after we crossed the Mississippi and started climbing uphill on the interstate at 80mph+ with a full load of people and luggage. I watched the supercharger boost gauge winding clockwise under cruise control and the car didn't miss a beat. We just sailed uphill past everybody else...

What make and model do you recommend. Auto Tap ?

I only have a code reader that is also capable of clearing codes and SES light.

Yeah as soon as I get some more dough I'll get one. Thanks for the hook up Will.

my riv must be different in some way compared to the Bonneville'*. the torque converter lockup is very noticable and is at around 40 MPH (or maybe it'* shifting into OD, I'm not sure. After it locks up it has a little bit of a shudder to it under acceleration. Also, at 40 MPH the car will shift into OD and loaf at 900 RPM! at 55 RPM it is only at 1,300 RPM. That seems low to me. I've never driven a car that was at below 1,000 RPM at 40 MPH. Now is this normal? lol. the gears shift as follows under 'normal' acceleration:
1-2=20 MPH
2-3=35MPH
3-OD=40
Torque converter lockup=45

guess I'll have to get that checked out. :( It doesn't seem to be off. when the car is gunned it shifts exactly when the tach gets to the red zone, not that it means anything of course. Maybe we can tell by the idle. lol. When the engine is totally warm it idles at 750 RPM.