Getting some misfiring on idle like small sudden drop in RPM and you can hear a muffled pop sound. It will be idling fine then i hear the sound and RPM drops slightly and pops back up. I noticed today when accelerating harder up a hill, I heard the puttering sound and noticed a break in the power of car then it came back fine. It really feels to me like a plug/coil/or filter problem. I'm at 35 K miles and the car probably almost certainly has had NOTHING replaced yet. What is my first thing to replace or check. I know the plugs and coils aren't a ton of money. Where can you get them for cheap? Any info appreciated!

 

You need to do a deep-level scan using something like a VAS5054A diagnostic. If you don't do the deep-level scan, you'll end up guessing. You may guess correctly, but most likely you'll end up doing something unnecessary or miss the real problem.

Plugs and coils are not inexpensive (depending upon your definition) and there is a considerable amount of labour involved.

 

+1
Get the Computer read out for codes. First and foremost!