05 vz idle hiccup

[Rod larsen]

My mate has a 05 vz after a service of new plugs, oil an filter, coolant. At idle it's development a hiccup can
anyone tell me what mite be the problem

 

[WL2005HBD]

If he replaced the park plugs, did he replace the gasket after removing the upper manifold? Could be a vacuum leak (I had same issue)

 

[Rod larsen]

Yeah not shore will find out. Thanks