backfire through SU and rough running

[Rod Shaw]

Thanks to all for the further comments.

The experience that some have had with some Bosch distributors is interesting and I will have a look inside mine and also check against one I have tried previously, as SJ mentions, and report back. IW's point on wet plug also good and I think I have covered this by trying one of the dry ones.

Thanks again - I will keep working on it!