1987 K5 blazer

I have a 1987 chev k5 blazer with a rough idle problem only on cold starts. It has 88,100 actual miles. its a 350 v8 with fuel injection. It has had an oil seal job @ 40,000 mi. Recently it has new distribitor, wires and new plugs 2 weeks ago. My mechanic has attempted to diagnose problem on 4 different days to no avail. Can anyone offer any help? Thanks