When the engine is stared from cold it idles fine - going by the dash revcounter it looks like it's more or less 800 rpm, and it sounds right. But as it warms up the idle speed drops, and it eventually stalls.
After, say, a ten mile run, the idle speed is still far too low, and it wants to stall.
I've checked my hoses and as far as I can tell I'm leak-free. New plugs, new distributor cap fitted.
Apart from the idle problem the engine seems lively enough. But a little thirsty. (21-22 mpg). As she's a little heavier than most, that's no surprise.
What should I look at next?