PLEASE HELP !!! 98 ML 320 ABS/ETS problem

[Mike_ML320]

Hi there to all of you Mercedes enthusiasts and specialists !
First of all let me say that I am a huge Mercedes "freak" and even after this bad experience I will still love Mercedes cars more than any other car out there PERIOD !!!. My first car was a 190 E, my second was a 500 SEC (the best car I have ever driven). A month ago I bought my third - a 1998 ML 320 with 145 K miles on it. After two weeks of driving it, I started to hear some rough noise comming from bellow the engine which very soon became very loud every time I would press the gas pedal. Just by where it was comming from I immediatelly suspected that there must be a hole in the exhaust pipe and I was very close to have it checked at a local Meineke muffler shop which now I regret so much I didn't do. Instead, I decided that as the new owner of the car I owe at least one visit to the Mercedes dealer to get an "expert oppinion" about all the possible problems I may expect to deal with in the future. BIG, BIG, BIG, MISTAKE !!!! I hope I won't insult any of you Mercedes technicians out there but one thing I know for sure is that I will never ever ever ever ... take my car to this Mercedes dealer again and I will make sure all my friends or any person I will come in contact with from now on will find out about my bad experience. I never had such a problem when I was living in Germany(Landstuhl) - I would always go to the Mercedes repair shop for any problem I had. The parts and labor rate are not cheap over there either but they never tried to rip me off or, even worse, to inflict additional problems on the car. Yes, this is exactelly the type of treatment I was offered here ( I am not sure yet if I should give the name of this dealer). They checked the car and came to me with a big list of parts I had to change "immediately". I don't know what made them think I look like someone who knows nothing about cars but when they told me that one of the biggest priority was to change the water pump I started to get suspicious because I knew that the temperature gauge never indicated such a problem and plus I never noticed any leak. Sure enough, there was no problem with the water pump - (I am still driving the car today and no overheating or coolant leak) and neither were all the other crap they were trying to sell me, necessary. About my problem with the rough noise, they told me they will have to replace both front catalytic converters - $2,300 job. Even though I belived them, I was determined to find a place where they would do it for a lot less. I went home, and the very next day in the morning I headed to the muffler place I initially had in mind for my problem.They first inspected it on the computer and told me that there was nothing wrong whith the cats. They found a leak and once that was welded, the problem was GOOONE : No more rough sound !!! The problem I am stuck with right now appeared after I ran over the first pot-hole, on the way back from the Mercedes dealer. The ABS, ETS, Brake lights and an annoying beeping sound immediatelly came on. I stopped, turned off the engine and restarted it few minutes later and the problem seemed to have dissapeared. Few days later, the same problem and the same fix only that the third time it happened the problem wouldn't go away by shutting off and restarting. This time it went into the "limp home mode" and I had to drive home with 15-20 mph. I took it to Mercedes dealer for a computer diagnosis and they told me that the ETS/ABS unit(pump) is bad and it needs to be replaced - another $ 2,000 job. Needless to say that I have the feeling they are trying to rip me off again. Leaving apart everything else they told me to replace and was not necessary, this is the reason I think the pump itself may not be bad : First of all, it happened every time I went over a pot-hole so my intuitive logic tells me it has to be a bad contact somewhere. Second, every time it rains outside, the problem is gone - no lights no beeping sound, nothing ( everything works fine) When it gets dry outside,the problem reapears and it drives me nuts because each time it goes into limp mode again. Once again, these are the symptoms : when dry, turn engine on and three lights come on -ETS, ABS, BRAKE ! When I start driving, immediatelly after I reach aprox.10mph , the beeping sound comes on and stays on until the vehicle comes to complete stop. Every once and then the car goes into limp mode( the speedometer is showing zero all the time and the transmission is not upshifting.
Any information will be highly appreciated.
Thanks!