96' Sub 5.7lit

My sub started running rough after you have run it to operating temp and then shutdown for an hour or so on restart. This happens with high ambient temps(above 90deg). After it starts acting up it lasts for about 5-10min and then goes away. Ses light comes on when it is running rough. Code is for #7 cyl. missing. No other runability issues. Recently changed to k&n filter. It appears to be a sensor issue, but not sure. Any suggestions.

Check fuel pressure and see if it drops with the engine off. Fuel pressure regulator could be leaking.

//2000CAYukon