What'd the temp gauge get up to? It could be one of a few things,
1) BHG, read this and hope it's not, i haven't seen many N/A's with BHG but it is possible
http://www.supraforums.com/forum/sho...hlight=BHG+FAQ
2) Air pockets in the coolant system, try parking the car on a steep hill so the fill cap is the highest point and so it'll get some of the bubbles out of the heater core, start it up and let it circulate then fill it again, till it quites making a "waterfall" sound in the dash.
3) The little rubber cap might have cracked and busted letting coolant out of the system, it's on the back of the engine on the pass side, behind the exhaust manifold, replace it if it's crusty or brittle.