Toyota Repair: Toyota stalls when raining, spark plug wires, dry weather

Question
I have a 1990 Toyota and this is the problem. If it rains the car will start no problem, after the engine gets up to operating temperature and the choke has come off then it begins to stumble.

It will stall and sometimes won't start again for some time. If I can keep it running for 10 to 15 minutes after it has hit operating temperature and the choke has come off the problem goes away and it runs fine, it will not stall again unless left over night when raining again. In dry weather there is no probelms.  

Answer
Just for your information, the engine is fuel injected and has no choke, all idle speeds are controlled by the on board computer but that is not your problem.
Here is what I recommend: replace the spark plugs, the distributor cap and rotor and the spark plug wires.