Technical missire problem with mk1 turbo

[87unoturbo]

hey engine is missfiring when foot is placed to floor at about 5000rpm or sometimes less. sometimes it dosnt missfire at all though? runs completly normally off bosot though,
does anybody have an idea as to what could be wrong?

 

[SmyTurbo]

Tryed a new set of spark pugs?

 

[Chas Uno]

runs completly normally off boost though,
does anybody have an idea as to what could be wrong?

Check for boost pipe leaks.

 

[Louie Bee]

Are you getting too much boost when it cuts? may be stuck wastegate causing overboost sensor to cut in (or out as for the spark plugs)

 

[gtirx2]

Old thread but thought i would reply.
Had the same trouble once and it was the throttle postion sencor was out of adjustment