I have a Montero sport limited with 200k miles. I've just replaced spark plugs and wires, valve cover gaskets, plenum gaskets, timing belt, timing belt sprocket, crank and cam sensors/seals, throttle body sensor, IAC sensor, water pump, alternator, fuel pump, fuel regulator, timing pulleys and tensioner. During the spark plug job, I checked engine compression and it was 120psi all around. During timing belt change, a rubber wire holder got caught up between timing belt and sprocket. I had to redo timing. I also changed out belt again just in case belt stretched. After putting everything back together, and start it up codes P1400 and P301 popped up and it was misfiring pretty good. So I checked the ignition on cylinder 1. Switch out coils with other cylinder and checked spark. All was good. I decided to check the compression on cylinder 1 since it in front and able to reach. Now it reads 70 psi. I'm pretty sure this the issue but what could be the possible cause? or what other test should I run to figures out the issues?