missfire

It takes double platinum plugs you could also have a vacuum leak.The plugs get changed every 100,000 miles.how long since your last plug change?

I change the plugs July 11, 2014

I change the plugs July 11, 2014

So most likely you haven't driven 100,000 miles since then?did you use double platinum plugs when you changed them last time?

I don't think I use double platinum plugs the last time.

Did you use copper plugs?

I am not sure what type of plug I use but I think they was autolite plugs they costs like $2.99 per pug. but I am not getting the good gas mileage that I got in the pass will the spark plugs cause the gas mileage to drop?

For 2.99 a plug I doubt you got double platinum plugs.They can a lot of things effect gas mileage though.Remove a plug and see how they look and how they look.

what is some of the thing that can cause a engine to burn more gas?

A vacuum leak like saturntech9 suggested would hurt gas mileage, also check the air in the tires, here is a guide on how to check for a vacuum leak.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

how much air to put in the tires will the amount or number be on the tires?

No the number on the tires is maximum inflation newer cars on the drivers door or drivers door label there is a tire pressure label.Your car gets 30psi front and rear.