Hi mate,
If you have fitted a dawes and Needle Valve, and got read of the ECU control/ Solenoid, Limp mode can also be due to turbo pressure going a bit too high with the extra load/extra pressuve on the throttle, whilsrt the revs are too low. Turbo pressure going up means more air being swallowed by admission and therefore MAF going up...
A bad MAF-Revs couple of values, and you get the limp.