The truck cranks over, it has spark, good fuel pressure, and compression, but it back fires through the intake

I have a 2000 Ford Ranger with a 3.0 Flex Fuel engine, I recently replaced the cam synchro and now the truck backfires through the intake. I followed all the steps correctly that I found online. I'm not sure if I'm on the intake or exhaust stroke for tdc, or if it's something as simple as a bad relay. Any help is greatly appreciated.