my sis lives in bottom end of thrybergh so next time im going down to hers ill pm b4 and nip to yours (im livin at dinnington atm)
Did you clean then plug intercooler sensor in b4 you blocked egr off or after.
The reason why im asking is because i starting to think it maybe ur egr valve/sensor fault, from what i understand youve blocked the egr valve physically but not tricked the sensor into thinking its still working. In order to do this your egr sensor has to be in working order but you can try for nowt (every saved penny counts these day lol)
The reason behind tricking the sensor is because its another bloody sensor the ecu uses to determine the pressure (sum crap anyway) when to close,open the egr valve. Now if the sensor or valve go faulty the ecu wont get a reading from the sensor and throws the car into limp mode (no turbo, well alot less power!!!) On later mk1 and defferently facelifts this would throw up CEL (check engine light on dash)