Multiple Problems

Hi, I have a 94 2500 with 230,000 miles. Ive got a number of issues and the major ones are getting worse. I searched threads for my specific problems but didnt have much luck.

First off, I bought this truck with 220,000 miles and the only mods that I know of are exhaust and k&n filter with no box. It smokes alot under load, more than my previous cummins (same year) so there might be fuel mods. I will number my problems starting with oldest first.

1. leaking oil all over bottom of engine, looks to be coming from passenger side lower front of block. There is a hose that is hooked in the block near there.

2.mileage going from 16 to 14 to 12 and now around 10 in about 2 months and fan clutch is siezed keeping the fan on all the time

3. occasionally when pulling.. the throttle sticks and the truck starts missing but so far has been cured by a full tank of fuel mixed with a quart of oil

4. A large amount of coolant blowing up all over the motor and going through about a gallon per 60 miles and getting worse

5. a large amount of oil that seems to be coming out of the valvle covers, This happened same time as the coolant problems.

Thanks for your help... this is a lifesaving resource!