Definatley your turbo mate. take off the complete intercooler - 4x 12mm bolts and one 10mm bolt undo both hose jubilee clips and yank it off, start your motor and go to the engine bay, give the motor a healthy rev and you will see that your turbo has probably turned itself into an oil drum barell pump!! For some reason when your turbo goes pop and you replace it with a "working - guaranteed ha ha " turbo they nearly always blow up again . I know because I put three "working - guaranteed " turbos on one of my starlets and they all blew up despite fitting them properly and starting them up slowly. I even bought a starlet to break (I needed a gearbox) that had a good turbo on it and when I put that one on it also blew. To keey your turbo running nicely its vital to do those regular oil/filter changes. Best way out is to get a properly reconditioned turbo / expensive but worth it in the long run,,,,,