Less than a day ago, my dad runs out and buys another Benz, a 1998 C230. You guys converted him, "We Were a Chevy Family! :P" He isn't car savy, and was rather careless. Its a nice car though, lots of optional stuff in it, paid 5k and its got 116k miles on it. Today we were driving around, he wanted to show me the car, the Check Engine Light came on. He was rather upset, I after doing the whole "I told you don't buy anything without having me check it first" decided to help him. I got it scanned a local mechanic. Code was PO170 "Fuel Trim". The engine dogs out at 4000 RPMs as well. (On, but power loss) I tried to clear the codes on the car using a Snap On Scanner, but it was unable to. After driving the light went out by itself. I'm not the most car savy person, but whats up? I read MAF Sensor, to lots of other things. It needs to be fixed ASAP as its due for a Jersey Inspection. What should I be concerned about? What could cause this? Also how much?

I found this, but its unfinished and the solution isn't listed. Any Ideas?