Can i have some help here guys?......the revs on my st205 drop off down to zero whenever i brake hard or change gear and more often than not the car ends up stalling......even when not in gear if i rev up to 3000 rpm and then release the pedal the revs crash below tick over and then bounce back to tick over again sometimes causing car to stall....its getting quite dangerous now and the car hunts a lot sometimes when waiting at junctions or traffic lights??.....and again goes low enough to cut engine out??.......if i turn my wheel slightly (power steering ) this tends to steady out the revs???......any solutions please?

Ian

you have a HUGE vacum issue.

When you use your PS the engine rev's up to compensate for the pressure differentiation.

dont toy around searching for the leak, go to your local auto parts store and get some snazy colored vac lines (kit) they r like 25$ and you can replace al your current vac lines, do them 1 at a time. also check your map sensor

Thanks for the help i will look into this

having any backfiring or other abnormal engine sounds?

No backfiring but i know my motec ecu needs a good mapping session...i know next to nothing about these engines i just love driving the car......these vac lines i am going to look at...which ones are they?....are they connected to the blow off valve?....any pics would be great help??.....
Thanks

yes to checking vac lines & sounds like you could a faulty blow of valve, give the engine a couple of revs from the TB and watch your BOV, sounds like its not closing/closing too slow ?