Have you guys checked motor mounts? It'* possible ...

thing is I tried to reproduce it last night with my brother watching the front wheels but I couldn't get the car to do it. It actually burns sticky goodyears on dry pavement quite easily. Both wheels each time. It seems that the car has to be operating temp and I have to be making a slight turn for it to happen

I may have found it. Gonna bring my car to the dealer with this TSB. "Launch Shudder" is the best description I can think of for my problem anyways. I notice sometimes my tranny likes to hang rpm on shifts.

http://www.automotiveforums.com/vbulletin/t513139.html


A/T - 4T65E Harsh Shifts/Shudders/Slips/DTC'* Set
File In Section: 07 - Transmission/Transaxle
Bulletin No.: 0O-07-30-002B
Date: July, 2002
TECHNICAL
Subject:
Slips, Harsh Upshift or Garage Shifts, Launch Shudders, Flares, Erratic Shifts and Intermittent Concerns, DTC P1811 or P0748 Set (Replace Pressure Control Solenoid Valve Assembly)
Models:
1997-1999 Buick Riviera
1997-2002 Buick Park Avenue
1998-2002 Buick LeSabre
1999-2002 Buick Regal
2000-2002 Buick Century
2002 Buick Rendezvous
1997-2001 Chevrolet Lumina
1997-2002 Chevrolet Monte Carlo
1999-2002 Chevrolet Venture
2000-2002 Chevrolet Impala
1997-1999 Oldsmobile Eighty Eight
1997-2002 Oldsmobile Silhouette
1998-2002 Oldsmobile Intrigue
2001-2002 Oldsmobile Aurora (3.5L)
1997-2002 Pontiac Bonneville, Grand Prix
1999-2002 Pontiac Transport/Montana
2001-2002 Pontiac Aztek
with Hydra-Matic 4T65-E (RPOs MN3, MN7, M15, M76)
This bulletin is being revised to add additional models and model years. Please discard Corporate Bulletin Number 00-07-30-002A (Section 07 - Transmission/Transaxle).
Condition
Some owners of the above vehicles with a HydraMatic 4T65-E transaxle may comment on harsh upshifts or harsh garage shifts, soft shifts, shudders on hard acceleration, or shifts erratic. These conditions may appear intermittently or set a DTC P1811 or P0748. During diagnosis, a low or high line pressure (actual versus desired) may be observed.
Cause
The above condition may be due to any one of the following which may affect line pressure output:
^ Sediment inside the pressure control (PC) solenoid valve, causing the PC solenoid valve to mechanically bind.
^ Sediment in the valve body, causing the torque signal regulator valve to stick.
^ Incorrect transaxle oil level.

Netscion, you are making it very difficult to follow your work. Please keep it all in the OTHER topic you have going so we don't wonder which one to get an update in.