01 jeep 4.0 no start

I have a 01 Jeep Grand Cherokee the head gasket
was bad but still ran, I drove into garage and
replaced the gasket and during the work the coil
pack fell from the car and broke, after getting a new
pack and all the work was done jeep won't start. I
checked all valves and torqued them to 22 ft lbs. I
have good spark and the spark plugs are wet with
fuel, my compression is around 140 across the 6
cylinders. When cranking I can hear it backfiring
through the intake. My question is how could the
timing be off? I didn't touch the timing chain and
the spark timing is controlled by ecm? Also I tried a
new crank and cam sensor with no change.