mk1 caddy pickup 1987 1.8 petrol

hi guys
can any1 help please my 1.8 petrol caddy on carbs starts great when cold, but when warm if left for 5 minutes  it really struggles to start.
its had new plugs, leads, coil, points, condenser, timing set with strobe light,  had a play with the carb but don't seem to make any difference
 anyone got any ideas please
thanks bob

I have also put a 1 way valve in the fuel line