Here lately i have lots of black smoke and fuel mileage has dropped off about 30%. Still have good power, boost and fuel pressure are good. Anybody have idea were to look for problem?

 

Sounds like an air or exhaust related problem, a restriction.

Check your air filter system and then your intercooler boots for leaks. After that if you still have the factory exhaust, the CAT-Con may be plugged.

 

New air filter, straight exhaust and boost pressure is fine.

 

I would still visually inspect the boots for any signs of cuts, expecially the ones at the intercooler.. They swell up under boost and contact the fender metal, can cut a pretty good gash.

When you say fine, what is fine?

 

Just all of sudden you have black smoke?Did you do any changes?

 

Have not made any changes. Boost pressure is 2lbs. at 55mph and 18-20 at WOT. Have 4:10 rearend.

 

Wow...your a little low on the boost side.If its not the boots,it may be a leak in the intercooler.Or is it possible the air horn gasket is bad??

 

Maximum Boost for stock Rams:
94+ 160, 175, 180 HP 15-18 PSI
96+ 215 HP 21-23 PSI
1998+ ISB 19-22 PSI . "courtsey of dodgeram.org"
Boost #'s look about right for a stock engine. my first thought would be injectors.

 

I had a very similar problem. Check not only the boots, but the intercooler itself. My boots were fine, although I replaced them, but the intercooler itself had a leak. I didn't sound like much of a "hiss" during testing, but after I replaced it, it sure made a difference.