I have read the Stumble and YoYo threads and completed the VGS modification on my '04 MCS. When the weather is warm I only get a slight stumble in the morning, then it runs fine. But now that the weather is getting colder (40 degrees last night) I get the stumble everytime I accelerate until it warms up. Any ideas on how to solve this? Thanks.

 

I've got the same issue. Just noticed it too after having the car for almost a year. Car is an '03 with 86000 miles. Any ideas as to what is wrong? I haven't done the VGS mod, but I'm not sure I want to go that route...(doesn't seem like it fixes the problem either...)