Need help with S-10

[275 pro]

I have an old 1989 S-10 truck with a 4.3 engine that has started to backfire through the breather when it gets hot. It also idles rough. This has just started happening and I'm trying to figure out what to do for it. This is my everyday driver and it is driving me crazy. Any ideas what could be happening?

[GM-Tech]

This is usually caused by a lean condition or a secondary ignition problem. What's fuel pressure like?

[275 pro]

Thanks for answering. I have two questions. 1 - this morning it was 28 degrees. The truck ran great. Why would that happen? 2- How do you check the fuel pressure?

Thanks for all of your help.

Ben