94 corolla several issues need some advice asap.....

[lifeisviewtiful]

a few things i want answered please if someone can help.

first off, my water temp as always at half, not at the quarter mark where i would imagine it should be. (would flushing fix this or is it time for a new radiator????)

my car runs very rough and sounds loud(light knocking sounds like it is coming from the back of the engine under the intake manifold. for the record, i changed the distributor cap, distributor cap rotor(i think its called), spark plug wires and plugs.

i see no second o2 sensor. i have one that goes into the exhaust manifold right in front of the radiator but further down on my exhaust manifold i have a spot where it looks like a second o2 sensor goes but there is none there and it look as if the flange is broken.

my car gets weak gas mileage. about 16-18 miles per gallon.

help is always appreciated, thanks guys

[94_Rolla_Guy]

half is fine thats where it sits on both the corolla's at my house 94 and a 96