1992 Ranger issues (answer and good kharma will follow:)

[scottwvu]

1. I have a 1992 Ford Ranger (2 wheel drive manual).
2. There is a popping noise when I am in gear and I either accelerate or de-accelerate (at the moment it "engages" or "disengages".)
3. There is a grinding, or vibration in the rear when I am moving and in neutural.
4. I have a problem. My check engine light comes on, and when it is on (90% of the time) it feels like I am loosing a lot of power and my gas milage goes to h.ell.

Please help!!!