Hi there. As a newby to this forum, please don't berate me for mistakes! Sounds as though something major has failed/broken/fallen off. Check the intake pipes, turbo connections etc. If there's a catastrophic hole in a boost pipe the engine will start but run poorly. I had a fault with my solenoid, but you seem to have ruled that out. There could be an air intake/boost blockage too. Good advice re. the timing/camshaft drivebelt, but if it's broken you'd get nothing at all. It may have slipped a tooth or two. I will keep an eye on this for any progress...good luck!