Toyota Repair: 94 T-100 V6 AT, Valve gaskets leaking oil, head gasket, exit ramp


Question
I need to replace the valve gaskets on my 1994 toyota t-100 V-6 Auto. It has approx 140k miles.
This past weekend my radiator blew and thermostat froze up. I had to drive approx 20 miles of stop n go to an area for tow. Replaced the radiator and thermostat and oil. The temp gauge not working but that can wait. The engine is Not putting out water in exhaust nor in oil. Added Lucas. The valve gaskets on both sides are putting out oil. I have a fire ext'r now. It will run with knocking at start up then as it warms up & sounds ok. It doesn't like interstate speeds, after 15 min on Hwy tried to idle off at exit ramp, lil gas & keep it going. a good bit of shaking and lil noise but I wouldn't push past 60-65mph.
Thirty minute ride = 1 Qt oil loss.
Valve Gaskets i know are $30-$40.
Obviously a professional is required but when one is not available ,I have to do this. Do i have to replace head gasket?
Is knock sensor easy to replace?
which manual is the best? Ulitmately,
What do I need to know and where do I find it?

Answer
If the headgaskets are not leaking they don't need to be replaced, just the valve cover gaskets. The noise and driveability issues may be related to a more serious problem, replacing the valve cover gaskets is a lot of work so it may be a waste of time if the engine itself is having a major mechanical problem.