[tomw]

I do not believe that the 3.0 has a balance shaft. I expect that the 4's might have one, but haven't looked.
I think you'll have to drop the exhaust to get the Y-pipe out of the way.
tom

 

[tomw]

The tensioners are expected to last into the 100's of thousands of miles. If you had low oil pressure, it is possible that the tensioner(s) got out of place. They are(I think) designed with mechanical 'steps' such that as they wear, they walk up the step, and take out however much tension, the oil pressure coming along when running, and removing any more 'slack' as needed, and if they wear more, then they will get onto the next 'step', thus keeping the chains mostly taught even with minimal pressure.
That said, I suspect it could happen. I did NOT listen to the noises.

A spun bearing can be perfectly quiet. How it does it, I have no idea. The rearmost main on a Ford 390 spun, no noise, no particular reason, and the rear main seal leaked heavily. No external signal the bearing was spun until I took it apart to replace the rear main seal. The bearing cap weighs 2-3 lbs, and is held in place by bolts about the size of my fingers... and it spun... no symptom except oil leaking... It got all new main bearings, and was just as quiet when done as before.
tom

 

[tomw]

The CPS - cam position sensor - is used to synchronize the injectors and ignition to the specific valves just opening, and the cylinder that should now be firing. The latter, more by the crankshaft position sensor, I believe.
The MAP will report what the intake vacuum is at the moment. If the valve timing was off, the vacuum would/could be very unstable.
The sensors just report, they don't decide anything. If they don't report, a code is generated, or if they report 'out of tolerance' values, ditto.
The MAP can cause power loss and unstable idle as it responds to manifold vacuum, and helps the computer figure out whether to lean out the mix when not working hard, or richen it up when the engine is under heavy load. The CPS is used by SEFI to fire the injectors right before or as the intake valve opens rather than the ganged or banked injector firing w/o a CPS.
tom

 

[tomw]

The resistance in rotating the crankshaft is the spring pressure on the valves. The chain turns the cam, etc, and the valves will open and close.

The tensioner on the chain is designed to need no replacement for a couple hundred k miles or so... not a normal replacement item until the engine needs to be re-built. (Actually is more than one 'wiper' part involved.)
The tensioner will be oil pressure operated, with steps that keep most of the 'wear' tension absorbed, so the tensioner only has to move a small amount under oil pressure to take up the slack. If the wear is enough, a spring loaded step will rotate one more notch, and raise the 'bottom' of the travel a bit, so next cold start, the tensioner would start from that step, and have little distance to go before all the slack is absorbed.
tom

 

[tomw]

One way to find out is to put compressed air into the cylinder when the piston is at or near TDC. If the air blows right through, you know.
A compression test will also let you know if you have valve damage.
I can't say if it is interference, but perhaps being only 90 degrees out may have saved your bacon, but if it had been more, time for some new valves. At least the 3.0 doesn't need the clearances measured and recorded to adjust the valves.
You can 'walk' the engine over to TDC on each front cylinder turning the crankshaft pulley bolt, and then use a leakdown tester {harbor freight l.t. $50 or borrow} to see if the cylinder holds air. I would think an adapter could also be fashioned from a compression tester, some fittings and a clamp or two to allow compressed air to be applied to the spark plug hole.
tom

Didn't this start out being about low oil pressure and the need to replace bearing inserts??

 

[tomw]

Well, if it ran without missing making the noise from the chain tensioner, then I would make the assumption that the valves were functional. If the valves were bent, and it would be on all 3 cylinders in that case, then the engine either would not run, or would run like crap. If it ran, pbt, and don't bother with the valve or compression check. Gap the plugs, put some anti-seize on the threads, and put back together(pbt).
I would.
tom