intermittant misfire

[wildchild74]

Right folks next instalment of the misfire saga.... drained 2 carbs n knackered carb 4 drain screw so couldnt drain it so went inside just to get away from it b4 i lost it...then thought f!@#k it and put in the stp n petrol and took it out gave it a good thrash now the misfire seems to be going but the revs seem to stick on at about 1500rpm resulting in no engine braking... will this go the more i use it plus will the treatment break down the blockage while its sitting in the carbs thanks
Gaz