VW Scirocco Mk2 1990 1.8 8v manual with Weber Carb - Random high & low revving engine! - daz9445

I'm having problems with a 1990 (G plate) VW Scirocco 1.8 8v which has a Weber carb fitted, a job done by a previous owner, and manual choke. It has only started recently but I've found that i don't need to use the manual choke on first start up. Even though no choke is being used the car will run fine 99% of the time ie not cut out, stutter, stall etc but when its been driven for around 15 mins or so the engine will start to rev high (2500-3000+) - feels like cruise control! Found that if I pull the choke out it pretty much cuts the revs and feels like the car is coughing - assuming thats due to too much fuel because of the choke being opened. Also found that slipping the clutch and revving up to pretty much redline seems to solve the problem but only temporarily. That said the car has also now decided it will do the opposite on occasions and will drop revs so when slowing down and down shifting the car will get to stalling point and it has stalled on occasions. Have also noticed that the temp gauge shows the car is only getting to around half of what it usually showed (Usually the gauge would be vertical or just slightly back from vertical but it now only goes to around half of that). The car has been serviced and a cam belt change done a few weeks ago.

Read quite a few forums and the waxstat is something that comes up most frequently but not sure if this is just for the pierberg carbs or is also relveant to the Webers.

Greatful for any pointers.

Daz

VW Scirocco Mk2 1990 1.8 8v manual with Weber Carb - Random high & low revving engine! - injection doc
i suspect its fitted with a webber twin choke carb and if so i would check the secondry throttle for sticking open ( a fraction)which will make it run rich and high idle and if the primary throttle has been adjusted to try and reduce the idle on the occasions the secondry butterfly shuts the car will try and stall.