I think a sensor problem would log a fault code.
I'd suspect a fuel flow problem (blocked filter, dodgy fuel pump) or a blocked exhaust.
agreed - if its ideling fine then not air related, seems to more starved of fuel....
Thanks for the suggestions so far.
The car is under going some repairs at the moment, last weekend I completed a Diff swap out, a very heavy job!! and also changed the manifold, the manifold I put on was also cracked, but not as badly, I have a feeling that the downpipe may not have gone on correctly, it is held on by one bolt and a lot of fire gum (bolts had sheared and needed drilling out, things started to go wrong from here!!), so it could be partially blocked, though the exhaust has a good amount of gas coming out, fuel filter was recently replaced.
I'm going to bite the bullet and buy a new manifold and genuine GM front pipe. (anyone have any nearly new items off a car they're breaking?).
Before I swapped the manifold out, the engine was idling fine, but having the same issue when being revved, so not sure on this one.
James