I have a mazda Etude BP 1.8L DOHC 1996 bought her from my brother four years ago, I live in White river Mpumalanga. I have recently had my engine rebuilt, yet two problems remain. Firstly she shudders when accelerating or decelerating in traffic and she jerks from time to time like the engine stops and starts? which i believe to be a throttle body problem or throttle body position sensor? Secondly when driving and i coast down hill (foot off accelerator) once i reach the bottom and proceed to accelerate again i get a puff of smoke out the back almost blinding the car behind me? I believe this to be crank case compression, which is the pcv valve? Please could i get any advice on both these issues please? I've also phoned all places i know to try and find a place that would stock Throttle body position sensor,PCV valve, and/or full throttle body, They all say sorry but I am going to struggle to get a lot of parts for the car?