Hi all

I'm having a few problems with my car. It just had the turbo redone recently (few 000 miles) and doesn't appear to be that.

Basically the car idles poorly (~750rpm) and if the car is reved to about 2000rpm then dropped to idle, the revs drop down below 750 then back up. If I try to move the car just on the clutch, it'll try to stall. All of which I believe is iscv (asked this before). Correct?

Also, at this moment as my car uses a standalone ecu set up and had no dv or recirc fitted as new, I'm seeing how the car runs with an atmospheric dv. It smells rich (has a decat fitted) and often has a little collection of fluid at the exhaust tip (was told normal on focus especially with decat). But I'm getting greyish dark smoke on overrun. There's absolutely nothing on boost, just occasionally on overrun, even if I hadn't been on boost. Also, if I allow the car to slow itself while still in gear (approaching lights etc) it's not smooth and jerks a bit. Is this all due to the dv? The spring in the recirc must have been weak as it boosts better now with a strong spring in the dv. Fuel economy isn't changed tbh. I'm going to do a ecu reset in a bit to see if that helps with stalling but one thing that I found that seems strange is if the car is idling and I press the brake firmly then take my foot off, the revs jump up by 250rpm or so then back down again. Normal??

I know I seem to know most but just wanted someone to confirm the rest for me.