Auto Parts: engine idle arm, small claims court, mazda dealer

Question
the mechanic that worked on my car before I took it to the Mazda dealer looked it over and said it was fine. I drove it once on the expressway and ever since its been stalling about every four to six blocks and especially after coming off the brakes following the wait at a red light the mechanic said the engine idle arm was bad but did not state if it was the upper or the lower the dealer commented that the previous mechanic did change the radiator but did not put on new hoses and the ones there are very soft and need replacing I don't want to be unfair in passing judgment on the mechanic but I get the impression that he wants to use this car, its servicing and me as a cash reservoir. He blew out the radio "so he said" when he hooked up a battery to the car its supposed to be replaced on the mechanics dime cause he ruined it but every time I go to the shop to find out if he has the replacement I get another story. Am I paranoid or slightly correct to be suspicious of the goings on.

Answer
As for the vehicles problem itself, i would eed more information of the problem and perhaps error cades if available. but as for the mechanic what you have there is a small claims court case.. Hooking up a battery would not short out a stereo, even if the polarity was reversed. the fuse would blow before anything..