renault espace running

i have a renault espace txe c reg runs but runs rough i have tried new leads and plugs and it still runs bad the carb keeps popping unless u accelerate hard and this seems to be ok for a min then will carry on popping it is running idely at about 1500 revs could this be a timing / carb /or valve problem does anyone know what could be causing this.

i have a renault espace txe c reg runs but runs rough i have tried new leads and plugs and it still runs bad the carb keeps popping unless u accelerate hard and this seems to be ok for a min then will carry on popping it is running idely at about 1500 revs could this be a timing / carb /or valve problem does anyone know what could be causing this.

Air leak, check the manifold gasket, base plate gasket.