I found this today while researching a problem I have with me 95
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 53-65-06A
Date: June, 1997
Driveline Vibration Over 37 mph (Replace PROM)
1994-95 Buick LeSabre, Park Avenue, Ultra
1995 Buick Riviera
1994-95 Oldsmobile Eighty Eight, Ninety Eight
1994-95 Pontiac Bonneville
with 3.8L 3800 Engine (VINs L, K, 1 - RPOs L27, L36, L67)
This bulletin is being revised to include vehicles with supercharged (L67) engines. Please discard Corporate Bulletin Number 53-65-06
(Section 6E - Engine Fuel & Emission).
Some owners may comment on a condition described as a "vibration", "miss", "chuggle", "hesitation", or "fishbite" sensation while driving the vehicle at 37 mph or higher.
With the Torque Converter Clutch (TCC) engaged, any powertrain or vehicle rotating disturbance is transmitted to the passenger compartment.
Important: Verify concern with owner before proceeding with correction.
Determine that the following conditions do not exist before proceeding:
1. Out-of-balance tires
2. Out-of round tires
3. Engine miss due to ignition related components or an inoperative mechanical function
4. A/C compressor cycling
5. TCC malfunctions causing excessive slip values as measured with a scan tool; or
6. Specific road conditions
If it is determined that the above conditions are not present and no other conditions are causing the concern as outlined in Section 6E3-B in the appropriate Service Manual, replace PROM (refer to ATTACHMENT 1). FOR SUPERCHARGED L67 ENGINES, CONTACT TECHNICAL ASSISTANCE.
This PROM will only raise the third gear TCC lock from 37 to 50 mph and fourth gear TCC lock from 45 to 54 mph for vehicles equipped with VIN "L" and "K" only. Refer to Section 6E3-C1 in the appropriate Service Manual for PROM replacement procedures.
Important: No other driveability issues are addressed with this PROM.
VERIFY THE CONCERN IS NO LONGER OCCURRING BEFORE RETURNING THE VEHICLE TO THE OWNER.
Note 1 The revised PROMS are not considered a 100% cure; however, most owners do not perceive the "chuggle" or "fishbite" sensation with the higher TCC lock up speeds.
Note 2 The revised PROMS may adversely affect fuel economy (usually less than one mpg depending on individual driving habits). Be sure to advise the vehicle owner of this fact.
If upon replacing the PROM the condition is still present, contact Technical Assistance for further instruction.
Note 3 For supercharged engines, review Corporate Bulletin Number 77-65-15 as another possible cause of chuggle.
I also read in a few spots on the web that the TPS can cause this along with wornout spark plugs and wires.
Wish there was a site with all the service bulletins for these cars, apparently this tcc lock up issue has sent many of these cars to the junk yard early because its so damn expensive to fix or even trouble shoot.
So does "PROM" mean that you can change the lock up speeds with a tuner or at the dealership or do you haft to replace the eprom in the computer its self ?
Just thought I would share this