MyVtec8yourV8

My 96 accord has been steadily getting worse an worse as far as the motor goes. Besides the ridiculous oil and coolant leak.
The car has been leaking both fluids for some time now. On a cold morning the car will smoke on startup and then stop less than 2 min later. I figure it's a head gasket mainly due to the look of the plugs.
I bought a motor up put in it I just haven't had the time to do it. As time has progressed it's getting worse. Not only does it leak somewhere about a gallon of oil every 2 weeks but it leaks a gallon of coolant in about 3-4 weeks. The oil leak is not an issue I care to discuss mainly because I have replaced every gasket and some twice.
Anyway I had been getting a CEL for o2 sensor. But it has still ran fine. Recently I no longer get the o2 cel I get p1300, p0301, p0303.. And the car runs like garbage. It stumbles, studders and even dies a lot at stop lights. At highway speeds it still studders but it at least it runs as long as I don't have to pass anyone because that won't happen. I try and the rpms just jump and I go the same speed.
I have replaced the plugs, wires, cap, rotor. Still no effect. Also I need to add that most of the time my cell stays solid but once in a while it flashes then goes back to solid.
So I'm not looking for a big fix for this motor because I have a replacement when I get time to put it in. I'm just looking for causes that may jake the replacement motor not run right as well as but me some time until I get the time to swap the motor out.