2001 Jetta needs help.

I recently purchassed a 2001 Jetta GLS 2.0, and I need some information. I'vve always worked on my own cars, and I'm tight on cash right now so I don't want to start replacing the wrong parts. Here's the deal: The check engine light is on, and sometimes, the car Idles rough as if it's only running on 3 cyl. I've heard that throttle bodies on jetta's either go bad or get out of adjustment, but I'm inclined to think this would not cause an intermittent problem. I know It's time for a tune up, so I'm going to at least replace the wires and plugs. What sensors should I consider replacing? The car has 116,000 miles on it, and so far, nothing has been replaced. I've heard that the mass air flow sensor is a common culprit of jetta problems, and that it's easy to replace. Is this true? Many of my tools were stolen recently, and I'm timid about getting into a big project. I just need to be able to get to everything with standard ratchet and sockets. What about the plugs? Are the easy enough to get to from above the hood? I just want to fix what needs to be fixed right now because the car also needs new tires and the driver's door has a broken hinge bolt. I'm concerned about the rough idle. Sometimes, on the freeway, the car surges, too. It will be running fine at high speed and all of a sudden it will have a bunch more power and start going faster. This is without giving more gas or shifting (it's a manual). Any info would be greatly appreciated. Thanks!
MIke

Take the car to auto zone or someplace similar to read the codes. (Free OBDII Scanner Rental) After you're armed with that information, catch us all up on what codes are coming up. I think it's a fair guess to say it could be the MAF (mass air flow sensor) but without any codes it's a blindfolded shot in the dark.