What do you think??

[MAC]

I had to pull my GPX over today and get it towed to a garage because all of a sudden it started idling like sh*t, the whole car was shaking. I could also hear a sort of unhealthy churning sound coming from the engine and the revs dropped so low it almost stalled. Its just time for a service, but i dont think that could be the reason so any suggestions? Anyone had a similar experience? I hope im not up for hundreds of dollars!!

thanks