2001 Renault Espace engine jerk/shudders and cuts out

my renault espace jerks after some time of driving than cuts out ,i have changed air mass sensor /egr but problem is still there .have hooked this to a diagnostic machine came up with air mass sensor/egr and these were replaced now its saying cam sensor ???any help would be great as i was told to put a blanking plate where the egr is located as this is open or closed causing the jerking and cut outs/and loss of power .replaced egr and after a week this had black soot deposits on the valve