I have a 2004 Tazz thats just been serviced, done cambelt, replaced all filters. Replaced plug leads on prev serice. Also recondit the carb due to jerking and mis-firing. The car is still jerking when changing from 1st to 2nd, and idling seems irratic. Should the idling be adjusted upwards? Car starts perfectly first time without the engine turning over. What else could be the problem.. could it be the fuel pump?