I am pretty sure I used the aluminum framed gasket but, I cannot find the receipt to confirm the part number. Is there any way to tell if it failed short of removing the intake manifold?

If the anti-freeze is not reflected in your oil level as much, have you smelled your exhaust? It sounds like its been slowly leaking for some time. And there is no external leaks?

An update! I've finally changed the plugs, and the ECT sensor. Power is definitely back up, and for a 16 year old car, I'm getting 17 mpg a first in...quite awhile, considering GM originally had said 18 for the city, I'll take that.

The engine is running rough when under load from the transmission, I'm not losing any trans fluid do I'll have to look into that, I'm also getting some extra pump noise, it almost sounds like a 'dry' pump, but I have coolant, and the power steering is still buttery smooth, so I've got to look into that as well, and my CEL light is still illuminated which is weird. So, thank you all, for all of your help. You gentleman are amazing.

the cel does not clear itself for a set number of starts if you dont do a clear with a scanner

I did not know that, thank you.

The brake pedal issue may be like the one I experienced a couple of years ago. I started to have some longer brake pedal travel from usual. Then later the brake failure light came on so I checked the reservoir and found it low. I replaced the brake fluid and bled the brake system and the light went out. Some time later the brake failure light came back on and the brake fluid was low again. Turned out the seals in the master cylinder wore out and the fluid was being sucked into the vacuum brake booster and into the intake manifold and burned up. Replacing the master cylinder and bleeding the brake system cured this issue. No problems for the last 2 years.

I keep forgetting to post my car. 1994 Buick Le Saber. Car currently has 91,600 miles on it. The car sat for a few years mostly and had issues that come with not enough use/maintenance. Such as infestation with yellow jackets and mice. No maintenance to the cooling system and infrequent oil changes but also very low mileage. When I got the car the radiator drain would not and required probing to remove the old coolant. Now it is clean and seems to work properly. It currently is having some problems with ignition which I hope to cure in the next couple of days.

What sort of ignition problems?