My wife's gray XC began stalling at stop lights a few months ago. She said it seemed like the gas pedal was not delivering gas to the engine. About a month ago I replaced the pcv system in hopes this might help. After getting everything back together the stalling continues. The car will start and idle at 1000rpm, after a few seconds drop to 200rpm, then back up to 1000, drop down to 200, do this a couple more times then stall out. I disconnected the MAF sensor and it didn't stall any more, but it didn't have it's old power at high speed. I replaced the MAF sensor today (new Bosch unit) and it still stalls out as mentioned above. Any ideas? Thanks in advance. This is such a great forum!

 

I retraced my steps in installing the intake manifold when I did the pcv replacement. It turns out I missed tightening the clamp from the intake air hose to the throttle control valve and that was letting air into the system. Tightened it and all is well. Runs like new.