Big Dean t

Impreza Year 2000 2 ltr turbo awd

When you Rev the engine nearly stalls and then goes up and down before it ticks over stable I've put a brand new MAF sensor as was told to try that first

Please look at picture.... Why is it when I connect the breather pipe to the dump valve or put finger over pipe tick over goes really low like it wants to cut out then shoots up again and dose it a few times before coming steady?? And how can I fix it ?

Yes there is suppose I could try that thanks

Alright guys I need some advice, I've got a turbo scooby and it's not idling right, if you blip the throttle the revs go up fine but when coming back down it bounces and nearly stalls and sometimes stalls. If it doesn't stall it'll bounce for a few seconds then catch it and smoothly idle.. I've changed the plugs, cleaned the throttle unit and changed the maff sensor, still nothing.. Any advice would be appreciated Thanks!