UKPassats

I had a tiny collision which cracked my grill and number plate. The car was written off class N so I bought it back from insurers. It was returned to me with a flat tyre and battery with a few bits "missing" from inside. When he started it up on flatbed it sounded awful! There is a loud poom poom poom from the airfilter area and if you try to rev it, even slightly, it sounds like big ends rattling. The first day, after warming up, all seemed good again but yesterday even after running for 30 mins it's the same. I'm sort of inclined to think maybe an injector or intercooler hose but would welcome any input.

Cheers
Dave