All three of the above responses are from experienced drivers of these trucks. I'd seriously take to heart what they are suggesting. Hopefully it's a relatively easy fix and you aren't going to have to go through a whole timing belt change again to find it.

In any case, I'd say your hunch to not drive it at this point is spot-on.

John B.

'87 Raider 2.6 Turbo Auto, Under Construction
'95 Montero SR, 35x12.5/15 BFG M/T KM-2's, Rock sliders, Qtr panel chop, gas tank lift, 2" BL, Aisins, 5.29s
'95 Pajero Mini
'98 Montero Winter Ed.
'04 Cadillac XLR
'03 Kawasaki ZRX1200R
'60 Ford Falcon 4Dr