Okay, heres the deal, I own a mazda b2300 and when I start it up it runs for about 15 seconds perfectly and then after the pressure builds up and it really starts running, it will idle up and down and threaten to stall out it runs extremely rough but this problem only happens when it is idling. I havent really tried anything yet cuz I dont wwanna put a ton of money into it without knowing if its gonna help, What I have done I guess is a full tune up but other than that I havent done much.
Terrible idling problem with my 1994 mazda b2300. on 1994 Mazda B2300
by Visitor in Lakewood, NY on May 20, 2011
ANSWER by DaveJM , May 21, 2011
Sounds like when the engine goes into "closed loop" -- the time when the processor starts relying on sensors and inputs to decide how to run properly -- that the engine stumbles. There are several things to check. I would recommend checking fuel trims - oxygen sensor operation. I would check the idle air control valve. Check for vacuum leaks.