Eddie, IMRC may be the problem, but it could also be heat soak, which all cars with open element filters suffer from.
As far as the situation you describe re; downshifting and passing on the freeway, what speed and RPM are you at? Did you know that 3rd gear will far exceed the legal limit?! Try that next time but be ready, READY, to shift into 4th right away.
Give me a call, I'll be happy to take a look at it for you.
Maybe you can drive my stock (for now) SVT for a comparo.
NOTE: not my car anymore...subwoofers, shiftknob!
Chip? don't do it, unless you have it done by ADC.
