Right, I'm the 'kid' who he bought the car off. First a few things to get clear : 1) Boost is a adjustable actuator which is set to 0.8 Bar, however I've known it to creep just past to around 0.9(Occasionally depending on circumstances)> 2) It has a HKS FCD which is behind the glove compartment, I never ever touched it from when I bought it but was setup to 0.8. 3) It has a turbo timer, a blitz one. Funny thing is the day I bought the car home it was torrential rain and did the exact thing, felt like engine was cutting out and juddering, but wouldn't do it if you built the boost up gradually. How did i fix the problem at the time? Replace the spark plugs, problem gone (Water had go in through the vent). So changed spark plugs and see what happens! One thing to consider is the Air filter being so close to the vent, possibly taking in water? I'm no experts but that could be considered. Just to clear my name here, I've not sold a 'lemon' car ran fine apart from the clatter which was clearly described and agreed by Paul (sticky lifter, shim problem). Like advised, don't go ragging the nuts off it until you've checked! I'm no expert but will try and help as much as i can here. Finally, I've not had any calls from you so I wouldn't of known, and if i did I would of been on here to help!