Noises During Shifting problems of the 1999 Dodge Intrepid

We have a 1999 Dodge Intrepid, for the last 2 years the same mechanical problems occurred. You would feel and hear a clunking noise, check engine light comes on and the car locks in low gear. We had a 5 star dealer service the car 10 times over the past 2 years. Each time they thought they fixed the problem. Now they tell me it can't be fixed. Daimler would not give us the time of day. They tell us we should go to a different dealer. We told them we were sick of getting the run-around, the response was: we can't fix your car over the phone. Imagine going 55 mph and having down shift into low gear.

1999 Dodge Intrepid ES 3. Vehicle frequently fails to be consistant with acceleration. Sometimes delayed transmission shift response even when using autostick. Transmission often seems to shift very roughly. Vehicle sometimes seems to downshift properly with proper engine response and has excellent acceleration even at 50mph when in automatic then sometimes has extremely poor and delayed acceleration and does not seem to downshift even at speeds slow as 35mph even when accelerator pedal is floored or stomped, which is dangerous when trying to get onto freeway, merging or passing. It is sometimes difficult to get vehicle to accelerate smoothly with accelerator pedal, lack of throttle action and very slow acceleration sometimes when pressing accelerator pedal sometimes half way down, then when pressed further and almost floored transmission kicks down hard, vehicle jerks forward and over compensates intended acceleration. Once when accelerator pedal was pressed down hard, down about half, not floored vehicle responded, accelerated and shifted much faster than ever before, vehicle had never performed this well or taken off so fast, was completely unexpected, vehicle went from 5-40mph in about 2. 5 seconds. The vehicle lunged forward quicker than ever experienced and the engine made more noise than usual. No complaints and actually like this type of vehicle performance but it is dangerous when the vehicle does not usually perform like this then all of a sudden does completely unexpectedly. I had to shift into autostick and downshift in conjuction with the brake to slow the screaming vehicle down. Due to some concern and trying to continually maintain the vehicle properly had five star dealership and service center where purchased replace and refill automatic transmission fluid and filter. Had dealership reset the vehicle's fuel mixture sensor and adaptive learn to factory defaults. This did not help. This issue is very intermittent and I believe dealer will not help.