I have been experiencing erratic/ occasional hesitation problems with one of my te wagons, It only happens after the car is started and idles , short trips. It will run fine going to the store ,then we get back in , it starts fine , idles low *500 to 600 rpm , once we begin to accelerate under light throttle , it hesitates greatly .Almost no acceleration ,SO I pin/floor it , and then it accelrates . At idle to 1500 rpm will continue to run rough . I then took it on the highway drive 100 to 120 kmh for about 15 km , and it runs fine again . It is comical as i try to get it to my "affordable MB tech " and by the time i get there it runs fine , never hesitates.Left it with him for a week and it never acted up for him .
The minute i get it back home , it runs rough again.

I have replace the following - fuel filter , plugs, ign wire(bosch) cap(bosch), rotor(bosch), seal, air filter.all within the last year or 3000 kms. Now I am thinking the 4 matic is going , so i tyt test mode , still no luck . I am still getting sporatic hesitation once monthly or when it gets really wet , or humid.
It seems to stop this,after highway driving.


Any help would be appreciated.

Lou. 1990 00 te 4 matic x 2