renault megan juddering

[cogsy]

my friends car (renault megan 1600cc t reg) has started juddering he has changed the spark plugs and ht leads, and had it put on a diagnostics machine still juddering any advice please

[TWR]

Wrong plugs, wrong leads. leads replaced the wrong firing order, crack in the rack.

[dm1982]

could be a warped clutch pressure plate

[iBrowse]

it might be cold?

[chas2008]

so what was the outcome of the diagnostics ?..
assuming it didnt throw up anything it points to a mechanical problem rather than electrics... ie, clutch, rubber mounts,brakes etc.. ,
Lagunas have an engine stabilizer which is a really common problem, allows the engine to rock..not sure if they are fiited to meganes though