Popping in exhaust

Popping in the exhaust always always ALWAYS means a lean mixture. The trick is finding out what the cause is. Have you started the engine at night with the hood up? This will allow you to see any acring going on with the plugs and wires. you need to get down in there and look REAL close. Be careful of the fan since it needs to be dark. Might even get a spray bottle with water in it and spray the wires and plugs and cap just to piss it off and see if you can make it happen. Don't jump to the most expensive thing first just because some armchair techs tell you that. 99 times outta 100 it's always the cheapest thing that goes out. Always start with the simple cheap stuff first.