Looking for some advice. 1999 328ic has only 47k miles. Have maintained it well, in accordance to BMW's inspection/service guide (including Inspection II 45k). Took it in for service due to low RPMs during idle & poor pick up. Dealer says it's a valve seal - cost to repair is $1800. After taking apart the engine to fix valve seal, certified dealer says it's an additional $3,800 to replace worn camshaft. Bunch of questions: has this ever happened to anyone else? are these 2 problems related? should it cost $5800? once the engine is torn apart to replace valve seal, what more labor is required to replace camshaft? am I being ripped off?