I hope it's nothing in the bottom end (i have 2 isuzus in my shop right now '98 rodeo & '99 trooper, rodeo is knocking & has big shavings in the pan & the trooper has a cracked oil pan/block). Just to make sure it's nothing serious, drain the oil in some container & check for shavings (small or large).

Another thing that comes to mined is your water pump. Did you change it when you did the timing belt?

"If i can't crawl over it, i'll fly over it"
rubo

'96 Amigo 4x4, 3.2L V6, 4L30E, D44 rear, SOA, 1" BL, undergoing surgery.
'00 Rodeo LS 4x4, 3.2L V6, OME 919 Springs, front cranked to match,1" BL, 265/70x16 Scorion A/T's.