I have a '95 pontiac bonneville with a 3800 series II engine that has issues with the antifreeze and engine.

no but they do have intake manifold problems.also make sure your head isnt cracked or warped.these are generally a very solid engine.

If the block is cracked it doesn't mean the there will be mixing. It just depends on where the crack is. You might have a bad head gasket and the coolant is seeping into the cylinders. In which gets the spark plugs wet and will cause it not to start! Injectors are notorious for going out on Pontiac's, at least I have had to replace allot. There's a few things you can do to determine what is happening. If your positive theres no mixing then skip step one! (1)- change your oil! If theres coolant then you know your engine is bad. (2)-No coolant in oil! Do a compression check on all cylinders. If one of the head gaskets is bad then you'll find one or more cylinders with low pressure. Try these things first if you know of no leaks any where. Good Luck I can't say anything about the intake gaskets being bad I haven't any come in with the problem. But its very possible because the VORTEC 350 had this problem real bad.

As stated before sounds like improper torque or a warped/cracked head. The 3800 is a solid engine with an excellent rep.

they don't really have head gasket problems unless the head isn't torqued on correctly. they do have a problem with the plastic intake getting a hole in it from the egr ports causing

coolant to fill the engine