Car started with bad idle in neutral and park (fine in drive), then loss of power on hills, finally crept down to a crawl on highway, eventually stalling. If allowed to sit for a while, would run another mile or so then the same thing. Had been set up and used with veggie oil (2 tank Plantdrive system)but after having this same problem last fall, system was bypassed to run directly on diesel. At that time and over the winter gas tank was removed and cleaned out, screen cleaned, engine breather cleaned out, filters changed (more than once) and the atmospheric compensator replaced. Finally the car ran fine, for several hundred miles and several months. Now back to square 1. Accompanied by some smoke and diesel smell. Seems to be getting fuel, as have one one of those little in line filters before injectors. They always have some air in them, could this be a problem?