1. its runs but not for long on tick over but if you keep them revs up it stays running
2. and when its been started a though time it will misfire and not start so i removed the spark plugs and they were all shity (they r new plugs) so cleaned them all up and it starts fine why could this be

P.s the car as been off the road for 8yrs and i brought it as a none runner and just rebuilt it can anyone help