lxm50sdn

I've got a 94 Explorer 2WD with the pushrod V6. I just bought it and one the quirks was dropping oil pressure under acceleration. I thought the oil return ports might be blocked so I pulled one of the valve covers today. It's sludgy in there but the oil is pooled on the right side (passnger side head) of the head (towards the front of the vehicle).

I've got three questions. First, can someone point out the location of the return holes. Second, is it normal for oil to pool in that location or should it all return to the pan when the engine is shut off. Third, is there a recommended brush type and diameter for cleaning those holes.

As always, any help is greatly appreciated.

Thanks,
Chris