Back firing Geo Tracker

Needs compression test. Cylinder leakdown test. Suspect valve problem. Some testing is needed.

Yeah I figured. It looks like a new head on it I will test and see

Will need to also verify no vacuum leaks. The new head work could have been done wrong or has developed a problem. By the way, next time you ask for help, tell us about the "looks like a new head on it" when you ask for the help in your post. That can make a difference in the replies.

I did leak down test they all test good why is it back firing so bad I tested coil from plug to coil power tested with in specs when I tested prongs it tested 1.5 ohms the specs say.9 ohms is the high

If spec is.9 ohms and your reading is 1.5 then yes it is too much resistance but may not be the problem related to backfire. What were the compression test readings? Did you check cam timing?

Compression was good and timing is perfect on belt and distributor and valve lash is good