Runing rich, help!

[Shadow182]

Bought the car:

I bought a 1999 Eclipse RS about a month ago. As I live in Vermont and I bought it in Florida I decided to drive it up. After a few hours I realized the car was eating gas like crazy, it was getting about 10mpg. It was also producing black smoke from the exhaust. Half way along the trip I stopped at an oil-change mechanic type place. He said all he could do to help is flush out the fuel injector system. This helped alot, bumping it up to about 18mpg. I've been driving it for a month now, and can't figure out what's wrong with it. It drives fine, seems like it doesn't have a whole lot of power, but I don't have another RS to compare it to.

Has some aftermarket parts:

GReddy exhaust, AEM intake, some aftermarket headers, and an MSD ignition.

I've tried a few things:

I reset the ECU as I've heard that might help, but it didn't. I noticed some damaged wires running to the O2 Sensor and repaired those as best I could, didn't help. Also, the check engine should be on if the O2 senser isn't working, right? The check engine light is NOT on. I had to get the car inspected a few days ago, and when the computer was checked for error codes there were none. I replaced the spark plugs the other day hoping that would help and it hasn't seemed to have any effect. The old plugs were Bosch Platinums and they were all black, typical of a car running rich. Also, all four of them were very wet. I replaced them with NGK plugs gapped to .050.

But it isn't fixed yet:

I'm trying to check everything that could be possibly wrong, but I'm running out of ideas. Any help would be much appreciated.

[BoostedSpyder]

if the o2 sensor wires were damaged, you may want to replace the whole thing. there was a guy in here that had issues related to splicing the wires of an old one and a new one.

[Shadow182]

Yeah, I'm going to test the O2 sensor to make sure it's working right, but I'm waiting for my multimeter to arrive in the mail. At $100 it's not something that I want to replace unless I know it's not working.

So, the other night I checked the PCV valve and it the PCV hose broke off in my hand, so I replaced both the valve and the hose. No noticeable difference yet. That's one less possible cause. Any more ideas would be great.

I've also noticed that my coolant gauge is a little wacky, it usually says the engine is very cold, even below the cold line. But, other times it says it's a little over halfway warm. I'm wondering if this might have something to do with it. Also, I heard that if your headers heat up too much they might throw off the 02 sensor with too much heat. Anybody know anything about this?

[RSLaser]

this is just an idea...but check the MAS airflow sensor and the plugs and wires. It sounds like mine and the plug was missni a pin when i bought it, replaced the plug and it ran great.