89 d50 2.6 no power

Girlfriend took truck and she said it started hard she gradually lost power until nothing and truck stalled. Checked oil was low but nothing out of the norm. It sounded as if something come loose under valve cover. I pulled valve cover off nothing loose. Checked timing, timing is dead nuts. Checked plugs and wires cap and rotor everything seems fine. It runs as if it jumped timing but its right on. Really rough running. I'm gonna check compression tonight and go from there. Any other suggestions. ? Thank you.

your timing marks on the cam and crank line up ?????

Timing marks on harmonic balancer and tag line up. The bolt on the harmonic balancer was loose dont know if that matters. How would i find out if crank and cam are lined up. I'm not really a mechanic but do have a little skill. Just cant afford take it to shop

pull the valve cover and see if the timing mark on the cam lines up with the crank mark

Timing was right on the money. I put stethoscope on timing chain cover and a lot of noise was coming from behind it. I pulled cover off and chain guide for oil pump chain bolt was broke. And "silent shaft" on driver side has alot of play in it, i could wiggle shaft and recreate the sound as if motor was running... i pulled shaft out and appears it has been heated up and some pitting on the backside of shaft.it seemed to me as if bearing race was worn... Now do i replace bearings and races and drill and tap broken bolt out. Or is there a elimination kit for this "silent shaft"....

replace bearings and races and drill and tap broken bolt out

how funny...... i have the tools to remove and install the bearings.... go figure