Either marginal compression or poor spray can cause the symptoms you describe. The only way to pinpoint which is to either remove the injectors for testing or do a compression test (or both). What is happening is the heat from the GPs is burning the fuel while they stay on so once they cycle off and they cool down the marginal cylinder is misfiring. You might be able to pinpoint it to which cylinder by cracking open the hard lines one at a time right after the GPs shut off and see if there is one hole which has a greater effect on the condition than the others...that way you will know where to start looking. You might even have bad DV seals on the IP which are causing poor injection due to air being sucked in. I have seen that cause the symptoms you are describing too.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz