1.5 carb wont run / rev when warm

Hi. My car run fine apart from high idle before I took the engine out a year ago. I have now put the engine back in and the car will start tick-over and rev freely until its warm. Once its been running around 5 mins it will idle put wont rev past idle it sounds rough and just cuts out. Any ideas?

So far I have replaced the fuel filter, put air down the fuel lines and petrol flows out freely. Fuel filler neck looks clean and ive emptied the tank, no muck came out and the petrol looked clean. Ive also taken the return pipe off and put it into a bottle and petrol was running out fairly steady. Even though I have a k&n fitted I down think its carb icing as the car was running fine until I took the engine out. Im trying to get an original air box so will try that anyway and also have some plugs on order. Starting to run out of ideas now.

might be worth stripping the carb down for a full deep clean and put a rebuild kit on it. poke/blow all the needles to make sure not blocked, check float isnt holed and accelerator pump works ok etc