kl31 or kl36

Im buying a KLZE soon and was wondering what the difference was between the kl31 and kl36?

...and also which would be the best ECU to run on my set-up?

either one is good...one was originaly used with atx tranny,s (kl36) and the other one (kl31) was used with mtx..but both works great
i have kl36 and can't complain

is there a difference in performance, durability, etc?

same

i have a 2000 jetta tdi 60k miles. last sunday when out for a drive, accelerated and nothing happened . continued to press pedal and it would not accelerate. what is wrong? please help

don't know..but might take a chance in the jetta forum...