Check your PCV valve.
Did you ever find the location of the pcv valve?
The pcv should be on the passenger side back behind the intake.
91 Ford bronco 5.0 you will find the PCV underneath the upper intake manifold toward the rear of the top of the valve cover. It will have a rubber vacuum line attached to it.
pass.side valve cover at the rear
The pcv is located on the passenger side of the motor, under the edge of the intake manifold, in the back.
Ford hid the PCV underneath the intake manifold, in the rear of the passenger side valve cover.
Is your PCV valve working okay?
Locate pcv valve on 1995 ford contour
The pcv valve is on the passenger side valve cover
***Check the PCV valve. This can cause a vacuum leak which most likely your problem.***
the pcv valve is located on top of the valve cover