ok more clues:

when i turn it off for a short time-- less problem
when i turn it off for like 30 minutes- bigger problem

after a "long" stop- it makes squeaking sqwuaking noises under the hood and last time the check engine light flashed...

i turned it off, started it back up- got it up to freeway speeds and it ran like perfect.

the reservoir "boils" as its running....like it's