Chrysler Repair: clunk and shake, acclerator, torque converter

Question
On a 95 dodge 3.3 intrepid while running at a concsent speed or in medium acceleration the car will give a moderate clunk sound and feel like it has downshifted (it is an intermitent problem the speed does not seem to matter)if you let up on the acclerator for a second it goes on like nothing has happened. Have replaced the cam and crank sensors, new coil pak, wires and plugs, new tranmission filter and fluid car has 148,000 miles. No codes showing up HELP

Answer
Hi Joe,
I haven't experienced that sort of behavior, but as you describe it I wonder if the torque converter lock-up feature might be releasing spontaneously which will case the engine to rev up about 10% which is almost like a downshift one gear but not as severe. I assume that you have a trans that is electronically controlled (has a "computer" for the trans). As I read the manual for one of these type of transmissions, this problem can either be cause by a problem with the hydraulics involved with the lockup solenoid (which would be serviced by servicing the valve body area of the unit and which doesn't require removing the trans from the car) or the mechanics of the lock up solenoid that may well require removal of the trans. It is possible to measure the pressure of the hydraulic part of the control thru a port on the valve body module and thus access whether that might be the locus of the problem. If not, then presumably it is the solenoid itself that is at fault.
There is another diagnostic approach if this seems to be a transmission problem and that is to have a competent trans shop of dealer readout the trans controller memory for any trouble codes it has stored. It might cost $50 to have that done but it would be a starting point for deciding what to do. The shop must have a Diagnostic Readout Box (DRB II) and the CCD bus plug and a capability to readout the fault codes on your year and model of car. So queustion them if this is the case. This readout is not the same as doing the engine controller readout so they have to have the cartridge (programmed capability) to readout the data about the transmission (again assuming it is an electronically controlled unit). The fault code for the lock-up controller is 38, so at least if you found that to be present it would corroborate my hypothesis. But still you would want them to check the hydraulic pressure before authorizing a removal and a big repain bill. The lock up just helps to reduce slippage in the drivetrain so it improves fuel economy by maybe 10%. Many automatics don't have this feature so you might live with it if you can get rid of the clunking.
As for the clunk, I wonder if that might not be due to one of the powertrain mounts that hold the engine-transmission unit in place having worn sufficiently to allow too much motion of the unit so that it is twisting as the engine speed increases and mechanically coming in contact with the frame that cradles the powertrain in place via the 3 mounts. That could be accessed by observing the powertrain when you shift from neutral to drive or to reverse to see how much motion you get and comparing that to what might be typical. If there is a mechanic or a dealer service shop that would look at this motion and tell you if it looks too loose then you could get a new mount if they would tell you which one(s) are worn out. So that might deal with the clunk part of the problem. I have the Haynes manual for this car and it describes the process:
"Here is the instruction from the Haynes on how to check the mounts:
The engine must be raised slightly to remove the weight from the mounts:
Raise the vehicle and support it on jackstands, then position the floor jack under the engine oil pan. Place a large block of wood between the jack head and the oil pan, then carefully raise the engine just enough to take the weight off the mounts.
Check the mounts to see if the rubber is cracked, hardened or separated from the metal plates. sometimes the rubber will split right down the center. I believe you will find three mounts (two on the engine, one on the trans)
Check the relative movement between the mount plates and the engine or frame (use a large screwdriver or pry bar to attempt to move the mounts). If movement is noted, lower the engine and tighten the mount fasteners.
To replace a mount, remove the negative battery cable. With the vehicle still supported on jackstands, remove the nuts holding the insulator to the engine bracket. From underneath remove the nuts holding the insultor to the frame.
Raise the engine with a jack and block of wood under the oil pan until the studs clear the engine bracket and the frame, remove the insulator and replace it with a new one. Lower the engine and replace the nuts on top and bottom.
Tighten nuts to 45 foot-pounds."  There are a couple of photos that show what the mounts look like. I could xerox copy the page and mail it to you.
Roland