Cutting out and engine temp

[Andyb7274]

Hello again, back again with a new issue hoping someone can point me in the right direction. Ford Focus 52 plate 1.8 Zetec has started cutting out when revs get too low and engine temp indicator never gets up to optimum level unless I've got my foot down (dual carriageway speeds), but as the car slows or nose is pointing downwards I can see the gauge drop to just above the white block. It doesn't cut out when it's cold (leading me to believe it's the automatic choke causing the issue). Cut out more noticable when changing into crawl speeds 10mph or so, but getting so frustrating I'm turning into Basil Fawlty everytime it happens, if anyone could shed any light it would be greatly appreciated. MAF has been checked, air filter clean, no blockages in airflow. Thank you in advance

[Andyb7274]

Can I also add now and again the car will emit a loud blast of noise when starting the engine, sometimes 1 long blast, others a repetetive tone, no warning lights, no indications anything is wrong as the car runs fine after this. Thank you again

[Andyb7274]

Bizarrely the engine cut out has resolved itself, still get the odd blast of warning beeps and bongs but nothing has happened, thank you for reading