Think I found the problem. Voltage from the ignition switch (at the starter) appears to be about 11.5 volts, battery voltage of 12.23. I'm suspecting that this is the weak link sometimes dropping even lower, although it doesn't really explain the temperature affect (lower temp, lower resistance, meaning it should start better when cold?). Either way, a relay can't hurt anything, and is inexpensive so I'll be doing that today and we'll see if that fixes anything.

86 4runner, pro comp AAL, Kayline Soft top, 31's but all stock