Take it back. Make him fix it. If he refuses, threaten him with small claims court. He'd rather fix it and never see you again than loose money + time + face in courtI have 1994 22re with 210,000 miles on it. I just had a new head, timing chain, water pump, all new gaskets and timing cover installed. Since getting truck back from mechanic the engine is very loud. sounds like knocking in valve cover. the sound is there at idle and while driving. I adjusted the valves yesterday and the sound is different but is still really loud. engine was quiet before work was done. also, i had a internal coolant leak which is why i had work done.
From your very brief description i'm betting its:
improper timing chain setup (guides/tensioner) which will destroy the motor
rocker arm hitting the valve cover (DOH!)
rod knocking (OUCH !)