My Dad just came into town with his 94 buick Lesabre 3.8L Automatic with 140,000km It has a real bad hesitation from stop under heavy accelleration. On the highway it gets up to speed and feels smooth but accellerates slow too. When you hammer it to full throttle on highway it does not kick down and go it just feels sluggish or like there is no power. Engine light has come on in the past and goes out. The scanner showed no current codes but old codes were: Heated 02 sensor voltage low, fuel lean and TCC error. My Dad pulled the fuse out for the ABS because it was not working properly. Fuel Press is 42psi key on eng off. It drops about 6-8psi when started. When you rev it up engine bogs down and press increases. I checked resistance in coils and they all apear to be the same 6.2 (not sure scale used). Wires are hooked up right and spark plug gap is.060in. Vaccume teed into fuel regulator reads 20hg at idle and 0 at full throttle. Coolant temp sensor seems to be ok. (Guage works and resistance varies when tested with multimeter. New parts put on were o2 sensor, IAC motor, fuel filter, Intake manifold gaskets, throttle body gasket, spark plugs and wires, we pulled off EGR and it looked clean. I sprayed wd40 at all gasket areas to search for vaccume leak but no change in idle.
I have had the same issue with my lesabre. It is definatley the TCC module. This controls the torque converter and can effect the drive of the vehicle. It is a $20 part and is easy enough to replace and should fix all of your issues with power. Because it has showed up in your codes history you vehicle is running in " limp" mode which puts the vehicle at it's minimal performance until the engine code is addressed. This means no power, limited shifting and poor gas mileage. Once the TCC module is replaced it should fix the problem. It is a poor design flaw by Buick and the best fix is to have the transmission repaired by AAMCO. THey will remove the old TCC module and bore out a bigger opening for the proper TCC module to go in, costs about $300 for them to do it.