I have a 96 F250 7.3. lately it has been making a popping noise though the intake. Really only heard it at idle or going really slow. So I went a pulled the valve covers off, replaced all the glow plugs and checked all the push rods. Found the bent one on the driver side in the cylinder against the fire wall. I replaced that push rod and reinstalled all the good ones. Torqued the rockers down to 20-FT/LBS. Started the truck and it sounded great, gave it a little rev and it sounded perfect. Turned off the truck and put the valve covers back on and reinstalled everything. Went to back out of the garage and as soon as I put it in reverse and hit the gas the noise came back but louder and at a much more rapid speed. I pulled the valve covers again and all the rockers and valves are opening and closing properly. I took all the pushrods back out to inspect them and everything looks fine. I cant find the issue. After the new pushrod was installed it only made the noise in drive, But now its making it in park as well. Any advice would be much appreciated.