Hallo everyone, iam new to this forum.I own a volvo 440 with B18FP engine.The problem has as follows.It starts ok,whether cold or hot and i would pretty much say it runs ok too.When it is in idle the revs fall approximately to 750 and then rise again to normal which according to the haynes manual is 850-950.The real problem is elsewere.The very first time i press the gas pedal immedietly after switching on the engine the revs drop lower than 750 as if the throttle switch or something is stuck.Also when driving in the city sometimes the revs fall under 850 and back to normal when changing gears or stopping at the traffic light.When i turn the a/c on it gets so worst that the engine dies as the revs fall too much and if iam lucky (after the whole cabin shakes) it idles back to normal.I 've been told that the ecu (bendix /fenix 3B) could have a fault,and that be the case i have to replace it.Once again the rev needle swings back and forth about 700-950 and with a/c at anything to 950.I absolutely love my volvo and i would be the happiest man alive if it was sorted out.Please help.