I have a 1997 4-wheel drive Blazer 6-cylinder
i changed my fuel pressure regulator, and now it is misfiring, and it seems like its out of timing. Please help.

 

Are you sure you got the plug wires seated all the way and in the right firing order? Are any codes coming up? And double check the distributor to make sure you put it in the same way it came out and that its not off a gear.

 

yes code po300