check fuel pressure under load. Check for bad/ plugged exhaust system. Need a lot more info , what does it do under what conditions. Engine temp how long has the engine run before problem shows, any codes, what are the fuel trim numbers on a scan tool. anything done to the engine before the problem started. I need a complete history
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1998 Fleetwood American Tradition 40VS
Cummins C8.3 300 HP Mechanical Injection Pump
Allison Transmission
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