Just started getting an annoying issue with my 2000 Blazer, it will start up fine when cold but if you've been on a run and switch the truck off for a few minutes then restart the problem occurs. The car will start immediately but it will run real rough and get lots of black smoke out of the exhaust tailpipe, it will stumble on for a minute or so then the engine will pick up to approx 1500 rpm then settle to correct idle. There are no trouble codes throwing up and no EML lioght on.

Any suggestions gratefully received as this is getting more commom a problem.