Still chasing the source of a shake/misfire

[Ranger305]

'92 Ranger 3.0 with the long block from an 07 Taurus. Changed headgaskets in the swap and used my fuel/intakes/electronics/accessories. Previous engine did not have this issue.

It as a rhythmic shake that is very noticeable from off idle to 1800 or so then isn't so noticeable. More pronounced as RPM decreases through that rage.

-New plugs/wires/cap/rotor/ worn dizzy gear replaced
-Vacuum test, very steady needle at 19" at idle, steady needle up to 2000rpm, just lower vacuum as you would expect
-Compression test, all 6 between 142 and 132
-KOER returns 111 and balance test returns 9
-Replaced the lower and upper intake gaskets, no change
-Sound test of injectors = ok
-OHM test of injectors, all in the high 14's low 15's
-Pulled and inspected the injectors, replaced 2 caps. All seem to pass fuel using a 9v battery, but couldn't evaluate spray or pattern
- No bent pushrods
-Fuel consumption seems higher than I expect (have owned this truck for 23 years)

Haven't replaced fuel filter yet (just got a new one)

The shake/Misfire is still there and I'm pulling my hair out. What the heck am I missing??? I'm pretty sure it is a misfire, but I'm at a complete loss what is causing it.

 

[RonD]

So you have a vibration, and suspect a misfire?

And no vibration unless engine is under load?
Motor mounts are OK?


Check Fuel Pressure Regulators' vacuum hose, should be dry no gasoline in there
Replace FPR if gas is in that vacuum hose
That will cause rich running a misfires

 

[Ranger305]

I also took the belt off to remove the front accessories from play and the vibration was still there, just slightly less obvious. It's not as noticeable under load, but is still there.

Motor mounts are brand new and it did this with the old ones as well.

I'll check the FPR and hose + replace the fuel filter.

exhaust does smell slightly rich. After I get a little more run on the new plugs, I plan to pull them and check the color/condition.

I'm open to other possibilities beyond a misfire, but not sure what else it could be.