geordi wrote:
Smoke and loss of power equals too much fuel, not enough air or boost.
Smoke is only caused by an excess of fueling, check your boost hoses for holes, but if this is an intermittent-and-fixing-itself kind of problem... Look to the MAP sensor possibly, or certainly the EGR. The stupid EGR might be sticking open, which would allow the boost an EASY path out into the exhaust, while the computer doesn't see the drop at the MAF and cut the fueling to match.
A block off plate and a GDE tune will solve that problem. Might also be a good time to extract the disc from the FCV at the intake elbow. Diesels don't need a throttle plate.
I concur with Geordi. Check and clean your MAP and MAF sensors. I went into Limp Mode a few times and had black smoke issues when my EGR/FCV were both failing.
It's time for you to get a GDE tune, seriously.
Invest in an hour and the Noob Guide, buy some non-chlorinated brake parts cleaner and clear up the MAP and MAF.
If you aren't going to get a GDE tune, you might seriously want to consider selling it now, as things just get more expensive the longer you wait.