Pleased that you appear to have resolved the issue, however I do have some thoughts. From your description of the setting of the base idle the blanking cap that covers the adjuster seems to have been removed suggesting someone altered the base idle previously which begs the question why? I assume your idle was running low before you made the adjustment? Have you checked the condition of the Spark plugs? I would also make sure the timing is correct. The thought is that adjusting the base idle is covering up another issue.
Glad to see it was straightforward and presumably set on the tacho as opposed roverguage? Always worth checking plug condition from time to time, but its not surprising to see idle settings may have been adjusted on 20-30 yr old car engines.
