SM25T many thanks, tried you idea with the acetylene torch and it has eliminated the throttle pedal pivot as the cause 😬, the (BRAND NEW) cable is free and slides ok.
Went out this morning no problem when cold, as soon as it gets hot the problem is back. Got the bonnet off quick but the throttle returned without any problems.
Then I had an idea , test it with the engine running, Hey Presto as soon as I did it with the engine at tick over the linkage took about 3 or 4 seconds close the last 5% or so and without load, revved quite high. Its as if the air flow into the engine is just too much and causing enough resistance to prevent normal operation, but only when hot.
To cut a long story (sort of) short, I have fitted an extra return spring and this has solved the problem, so now I have to decide if I pay the horrendous £118 for the puka Jenvey throttle linkage or fabricate my own arrangement.
(Phil thanks just seen your advice, will give the Jenvey throttle linkage a miss, I don't like the way it sits so high on the top anyway).
Got any springs in your garage Brent?
Guy
Now with MORE bhp HERE