Lumpy idle till 2000k then smooth?

hey laddos, not been on in a while forgot what a box of mk1 tresure this place is!

little question any input welcome…

Got a mk 1 gti , with a small block audi 80 2ltr running.

done all the conversion correctly.

but lately its developed this lumpy idle, feels like its not burning on one of the cylinders, and you get a strong smell of unburnt fuel when statonary, this happens till 2000k then it runs smooth and pulls lovely again

just very nasty before then..

just about to go have a look under the bonnet, any idea's people?

air leak?
Bert

funny enough that was a contributing factor, one of the vacume hoses had a split!  all mended that but still lumpy.

took out all the plugs all a nice brown hay collour except one of them which was sooty black. its defenately not an ingition problem..

just down to the injector now, and will need to check the compression.

one of them i guess..