1998 Oldsmobile Intrigue cant find leak

There's no such thing as a "Water Heater".

Also, it's never a good idea to hunt for a problem by removing/replacing parts. It never works and only cost you money that could've been spent on a mechanic.

If you don't have a coolant system pressure tester (150 bucks), the next best thing to do is jack up your car at all four corners and place it on jack stands. Start your engine and get under there and look.

If it's coming from the engine compartment, then its coming from the engine or where the hoses enter your firewall going to your heater core.

It could be a leaking intake manifold or the crossover tube that goes from one head to the other.

Your coolant can also leak from the heater core, but that would leak inside of your vehicle.