Escort cossie wont turn off

im buying/bought a 1993 escort cossie, standard spec. its a nice car but has one major problem.

it wont turn off!

you can even take the key right out and ignition, lights etc all go off and it still runs, only way to turn it off is to stall it!

I thought it was the small metal sensor held in buy a plate and two screws to the right of the inlet mainfold, which i think is some sort of fuel,air mix sensor. i was told as the car was standing for over a year there valves sometimes need cleaning out, as they stick open and the engine runs on buy sucking fuel in?

this has been cleaned out througherly but the problem still remains!?

all i can think now is the actual ignition barrel is faulty. i also notice there was a clifford alarm fitted in the past, but its has only just developed this problem so dont think its anythin to do with this being removed.

Anyone else experience this or got any ideas, i can live with it for now but its going to bugger my clutch before long?

thanks in advance.