Need help. Ahhh.. 2004 ford focus

[damo76]

Hi guys, been a while since I have been on here.
But the step son bought a 2004 ford focus, the European one.

Anyway, it's got a issue.
First it was dead on cylinder 1 , I changed spark plug.
And it seemed fine for a couple of weeks.

Then it started running sick.
Low idle in gear to almost stall point.
When you first take off it has a miss then seems to get better at higher revs.

I changed fuel filter which was old, pcv valve hose was cactus so changed that.
But it's still sick.

Air bag light flashes randomly, but no engine light.
And because it's European, the code reader doesn't work on it.

Any idea please?

Thankyou