Rev, Sorry I have not got with you to come by the shop but been very busy trying to get a car done, will get with you soon.
On your car I agree with Tom I think your turbo is going into surge that what the strange noises are and the loss of boost and inconstant preformance. The turbine is too small and spins the compressor so quick that the engine can not use the air and is backs up. you need a larger turbine not a/r but a larger wheel I hate to harp on this but even the 250 six is a large motor and needs a big turbine wheel. Also the lean mixture makes a lot more heat and adds to the problem. Just my thoughts Harry.
