2000 Dodge Neon

So far I have had done on the car is this: the idle speed valve has been replaced, I have had cruise control installed on the vehicle, the Intake manifold has been replaced, and I have installed new spark plugs. When I replaced the spark plugs I found oil in the well around plug number 2 but figured that just means I need to replace the gasket there. That pretty much sums up the maintenance that I have done or had done. I did also notice that the dip stick has a burned on oil residue on it which comes off by scraping it with a thumbnail; I guess that means that the engine has overheated at some point before I owned it. Also, before I owned the car it had a minor front end collision which broke one of the brackets that holds the air filter housing. There is also a crack on what appears to be the distributor that has been sealed with some sort of epoxy. I hope this new information gives some sort of a clue as to what the problem might be with the car.

Thanks. I'll try replacing the sensor.

W had a 2000 and put in bosch platinums and noticed our mileage go down and the idle was off
check the plugs and put in plain old champions if thats not whats in there. For some reason the dodges don't like the fancy stuff!

Thanks, I'll check into that.

I replaced the coolant temp. Sensor and while it did make the gage in the car read a little bit hotter than it did before, it has not fixed either the fuel mileage problem, or the hard starting/stalling in cold weather. I did however find that the bottom half of the air filter housing has been shattered and that the throttle body assembly is only about half attached to the air filter housing due to a gaping crack that travels around three sides of the throttle body. I don't know how much this will affect the operation of the car but I'm guessing that it doesn't help. Any input on this would be most welcome. Also, I had recently installed "Autolite double platinum" plugs in the car. Are these as bad as the Bosch plugs I've been hearing about? I have heard that for some reason neons are particular about the kind of plug you use and ordinary non-platinum plugs are the best. I don't really understand why this would be, except for maybe a small change in the resistive properties of the plug. Anyway, if this is so and someone could explain it to me I would be grateful.