Originally Posted by RonD
Yes, if both banks go lean.
Your '99 should have 65psi at the rail.
You can rent/loan Ford fuel pressure testers at some auto parts stores, or tool rental places.
Or make your own with gauge that goes up to at least 100psi.
The test valve on the rail is a schrader valve, so the same as a tire air valve
Fuel pressure was 65 on the money.
So, I may have solved it. I went under the the truck to check out how difficult it is going to be to get to these O2 sensors and I notice the oil filter was a little oily - not dripping, but certainly not clean. I also notice oil on the engine near the filter. The filter was not as tight as it should be. I could hand tighten 3/4 of a turn. I put the ODB meter back on and the long term trim levels look better. I'll take it for a ride this afternoon. Could that really be the answer or is it just wishful thinking?