when i bought my 9000lpt 1997 it had been standing for a year or so. when i drove it overboosted until cut out. took the car to garage bloke prodded about the wastegate area and told me to try it now. i did and everything was fine for 6 weeks, now for the last few days, when i use full power after warm up it cuts out, and then seems fine. is there any thing i can do ? is the wastegate sticking or should i look at a new wastegate.