90 20v Q - Kangaroo...

[DERV_Monkey]

Hi all, just got my '89 90 20v Quat out of short term storage and have been driving it around over the past 3 days. It starts instantly at all times and when the engine is cold it seems to have loads of power and sounds awesome. Once I have been driving for 5 mins or so the engine note will generally change and it will become very down on power with hesitancy right through the rev range except WOT whereby it will always, without fail, clear and shoot off like a rocket. On half throttle it will kangaroo like hell and can be very embarrassing! The other thing is the car is extremely fumey and I cannot have the windows down without being gassed!. Also the temperature gauge is very erratic sometimes not moving off cold and then other times going straight up to temperature (I have not noticed a correlation between poor performance and non functioning gauge). Can anybody give me some pointers as to what is going on?
Cheers,
DERV