Thanks Guys,
Took it to a local garage for diagnostics. Plugged, said 42 codes on it...could not read them though (needed to go to Lexus maindealer!)
Tried resetting the ECU by pulling the fuses out as suggested in another post.
Lights all went out, looked good! 4 miles up the road, lights on, limp mode back. Bugger!
Switched off, limp mode off. But came back even quicker than before. Switched off, limp off, back quicker again...seems to be getting worse!!!
Having read through the suggested post given above, I will try the EGR valve clean first.
Will have to wait for the weekend though.
will update after EGR clean.
fingers crossed