93 misses out

[sparky9494]

i have a 1993 24k kept in garage. starts fine if i drive for 15 min. stop for coffee when i start up again it runs rough ,lacks power, hear popping in exhaust for about 15 minutes then it smooths out and runs fine . any ideas ?

 

[Vette_Newb]

Sounds kinda like my Tahoe when I had a blown head gasket.