1999 Chevy blazer 4wheel drive

Do a compression check on all cylinders, & test for exhaust in cooling system to see if a head gasket blew, Intake gasket could of blown and it could have had nothing to do with a gasket but to confirm is important as to what happened, If engine is low on compression and head gaskets are good then you know the engine is bad or needs rebuilt, buit if gaskets will solve this then you can do gaskets instead of the whole engine, and like I said above may not be a blown engine either, but have to start somewhere. I would also look it over real well to see what you can find out along the way, like fluid levels, bad looking hoses, leaks things like that and see if spark plugs have any indications , find a chart on the net to show signs of how your engine is running by comparing the spark plugs to a picture chart.