I have a 98 Dodge Avenger Sport and I went to AutoZone to get the Check engine light codes read, and what it gave me was P0300 and P0301 -Which according to my haynes manual is "Multiple cylinder msifiring detected" and "Cylinder no. 1 misfire detected". I'm guessing this is what is responsible for my sometimes rough idle and acceleration.

Is it harder than it seems to remove the intake manifold and are there some trouble spots that may not be evident? I looked around the manifold to see what items the guide says to remove and it did not look that hard but since I have never performed this level of repair I am a little apprehensive. If I take it to a mechanic they will charge me $280 (including parts) to replace the plugs, wires, cap, rotor, and fuel filter - basically a tune up. Should I let the mechanic handle it or should I attempt it myself and if so what parts/tools should I get.

 

Welcome to DF SlicedBread.

It's not a hard process at all. Just remember the few hoses that are attached and even that you really won't have to do because the manual can help you there too. The plenum uses a metal gasket I believe, so you won't have to buy a new one since you can reuse the old gasket. Just be careful with it.
Tools aren't anything special except for needing a sparkplug socket. I don't think it's worth taking it to a garage because it's an easy tune up...you'll see

 

Why are you removong the intake manifold? Change the plugs and wires and clean the throttle body. The problem should go away without removing the intake manifold.

 

I'm assuming that it's a V6 and to reach the back 3 plugs, you have to remove the plenum.

 

Just one more reason I am glad I got a 4 cylinder instaed of a V6.