Your cars engine management system identifies misfires and shuts down the offending cylinders fuel injectors till the next key cycle, where the process starts over.

You probably have a secondary ignition misfire and it has probably been fault coded in the HFM controller. You need to read the codes or just try replacing all the connectors beneath the three colis. A coil also could be the problem but the intermittancy points to a connector. Replace all three they are cheap.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician