Well im guessing your upper plastic intake is cracked..its defintally an issue with the non-supercharged 3.8'*
this tech info submission is based on a Series II but should give you a good idea..
thats if this is the problem
Have you checked the thermostat housing..there is a little pressure screw on the top of it, is it tightend down? Is the gasket any good? Old thermostat?
Id check out the cheap things first!
Im sure a few gearheads will reply to this as well!
P.* Welcome to the Bonneville Club!!
Damien-they don't make them like this anymore
97 SSEi. 3.2mps,msd,optima,1.9 YTs,245 RE750s,SLP Headers,custom ported SC inlet/outlet, 180 deg, INTENSE pcm,42.5#injectors,255lph pump,custom soilid motor mount, 3.0 mps(maybe), and the nut behind the wheel.