98 Lincoln Navigator that has a really bad idle and doesn't stay running!?

Jackie

New member
Here's what's been done; I've replaced the Idle Air control, fuel filter, air filter, fuel pump, pcv valve, and egr valve. Pressure tests are fine on the cooling system. Pressure tests on the exhaust where weird, it was bouncing between vacuum and pressure. Intake manifold vacuum test was doing the same thing. It's aslo not throwing any codes either. Any ideas?
The intake is aluminum, not plastic. I'll check out the elbow hose/fitting tomorrow and put in another update. Thanks for the idea!
 
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