LOL, did I miss something?
Sludge builds up from not changing the oil [enough] and from not getting the engine warmed up enough while driving it (drives that last less than 10 minutes). If you constantly make short-trips, you should change your oil more frequently.

Here is a maintenance interval breakdown for the Neon:
https://dodgeforum.com/forum/2508248-post2.html

When you change the plugs and wires, you should change the PCV valve, oil and oil filter too then just in case. An oil change is cheaper than a new engine. Also, being over 105,000 miles, have you done the timing belt and water pump, etc., yet?

 

The 2.7 had horrible sludge issues. 125k miles or so and it'd be pretty sludged up.

I agree about doing a full tune up. It'll help a lot. Do you live in a state that gets winter blend gas?

 

winter blend ???? i did my timing belt when i did my water pump imgoing to regap the plugs see if that makes a difference if it does ill get new plugs thanx tschay

 

What state do you live in? States that have cold winters get winter blend gas which contains a higher amount of ethanol.

 

Not sure about that. Out here in Kalifornia, we have two different blends of gas because the "summer blend" has additional stuff in it to help reduce emissions in the warmer months, or so we're told. In turn, it also makes gas more expensive in the summer. Woooo.

 

pa ,tschay

 

you dont have to remove the throttle body completley, persay: I took the 4 bolts off the box plate and unscrewed the hose clamp to the bellows tube and disconnected the brake booster vaccum line and left the throttle a cruise cable stuuf on it and I was able to clean it with soap an water and a sock. and the other sock to dry. I did take off the bellows tube and cleaned it aswell, and wiped as far as I could in the intake to remove oil from pvc, wasnt much there tho. My throttle body has a good amount of black soot stuff behind the plate, so it is worth cleaning. I did clean my IAC valve to, I sanded the outside of it to, because aluminum looses its finish.

 

You guys are kinda like the red headed step child of the U.S. lol. From talking to a lot of guys that live in cold weather states on the other forum I'm on, they get winter blend gas and it drops mileage. That's with new vehicles vs a 12 year old vehicle that was built/tuned for non ethanol fuel. There's a gas station near me that sells non ethanol 89 octane and I notice a difference in idle and driveability than when I use the E-10. Go here and find a gas station around you that sells non ethanol fuel and fill up with a tank of it. See if it makes a difference. http://pure-gas.org/

 

Oh, totally. There's ethanol in everything out here. I don't believe extra ethanol though it what's added to the gas. I'd be willing to bet that there are hardly any gas stations in CA that are ethanol-free, and if there are any, they are probably 91 or 93 octane, lol. The trick is, not getting E-15 gas :S
Though, there is a very small gas station very near to me that I recently started using and I've been getting better mileage out of both cars I've been filling up there. Maybe they are a hidden gem...