my 96 is doing the same thing, dose it do it worse when someone rides with you, mine dose, i put new fule filter same thing, new plugs and wires also. I am changing the lim gasket today, my last motor did the same thing and locked up bc of the lim gasket, it took me about 2 hr to tear down geting ready to get the parts and put back togeather, check for coolent leaks around the mortor or oil in the coolent