I am having a problem of engine surge at idle in my MK2
1 the Auxiliary Enrichment Carb (AEC) will switch on to start, however, I usually need a shot of either to have the engine start initially. Engine fires up immediately
2 Once started the engine will surge to 2K RPM, then back down to 800 RPM then back up to 2K RPM,
3 I can turn off the AEC (totally isolate from the battery) but the engine will continue to surge up and down until the engine finally dies at the lower RPM
4 Even with the AEC disconnected, the needle valve on the AEC will rise and fall in sync with the engine surge.
Any suggestions as to where to start to troubleshoot?
Thanks in advance