Hey there all..newbie to the forum in seach of the that perfect day when my wrangler runs like a dream

Ok here goes..hope someone can suggest a remedy. I have an 89 wrangler. When she starts from cold in the morning she runs well, idling steadily at about 8,000 rpm. However, after driving her for a bit and the engine starts to heat up the idling becomes eratic when she comes to a stop. It kinda lopes between 8,000 down to about 3,000 rpm..sometimes so low that she dies on me. I've looked at the Haynes manual and they suggest about 10 possible different problems, the first being vacuum leaks..but I see no chapter on how to check this or where to check. If anyone can offer any suggestion as to what to check first or what they think the problem would be I sure would appreciate it.
Thanks
Stephen