a few things to check. first, if you havent done so, replace the fuel filters, and air filter. while you have the air filter out, check the small 3/8" rubber hose, about a foot long, that is on the turbo, runs to the waste gate, look it over very carefully for holes, cracks, etc. give that baby a few sharp tugs, then just go ahead and replace it since it maybe clogged with gunk!!!
3/8 fuel line will work ok, oil resistant hose is better. then check the hose that runs from the back of the intake manifold, to the soleniod on the firewall, and then to the aneroid valve on the fuel pump, small, clear or white plastic line, trace it all out and look it over very closely like above. ill sleep on this tonite, im beat now, if i think of more ill post tomorrow!! good luck!!
matt