99 ford ranger with ck engine lite and missing

The code read #3 so changed the plug and coil and was told it wasn’t the valve stuck open. What do I look for next. It is still running rough and the ck eng lite is still on

[b]Here’s how diagnose this misfire code.

Click on Who’s At Fault?

http://www.underhoodservice.com/

Tester[/b]