it is entirely possible that a leak in the pipe is sucking air into the system. Not all do but if air is entering then there would be a negative response from the computer. I am not so sure the results would be a richness that would cause sputtering and almost stalling.
What is the engine doing at the times this happens..Pulling a load such as a hill or lugging in a gear? Does down shifting help? Does it do this while ideling? Give us some help here.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

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