Could it be my main relay if my car trys to crank but won't startt

If you replace a part and it makes it worse, put the old part back in and start the diagnostics again. It is also possible to buy new sensors that are faulty, especially the ones made in Mexico! Never buy cheap sensors, buy the OEM ones that the maker used.

A $5,000 professional scan tool computer will tell you exactly what the issue is with the vehicle by reading historical and live data.

https://www.google.com/search?q=2006+Ford+Fusion+V6+won%27t+start+after+changing+the+crankshaft+position+sensors

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just a couple thoughts. Injector fuse and relay(does fuse and relay have power to and from them). My understanding is sometime Anti theft will shut down injection pulse so car can not be run. Maybe even timing chain broke. I assume there is no trouble code.

Engine cranking, check primary voltage to ignition coil, dark green wire with orange tracer. Use a test light. That is the same voltage circuit for fuel injectors. That voltage comes from asd relay. I'm not saying the relay is faulty. The computer has to see both the cam and crank sensors signals or it won't ground the relay.
Could be other issues? You did visually check for spark at the spark plugs?
Any applicable trouble codes?

Check the fuel pump. Fuel pump relay. Car security system.

check fuel filter,vacuum leak,fuel pump.

Hello, It seems you have done a lot in trying to fix this. My first idea is that it is a pickup sensor for the camshaft or crankshaft. The firing order of your engine is 1 4 2 5 3 6. You are having misfires in 3 consecutive cylinders 4,2,5. This would seem to mean that the distance to trigger the firing is greater on 4,2,and 5 than on the other 3 cylinders. This can mean you have a lopsided situation on either the crank pulley or cam. You should see if the crank pulley is tight as well as the cam or if you can better adjust the 2 sensors.

Next, the Intake system can have a bad gasket. Use a water spray bottle and with the engine running, put a mist on the Intake gasket. If you have a change in RPM, then you have found a leak. This would explain why the same 3 cylinders are always misfiring. Some of the V-6 models used sandwiched 2 piece manifolds and the gasket between the upper and lower half would deteriorate over time. Some engines used "runners" between the Intake manifold and heads which could gum up over time. Just a cleaning operation if you are putting on a new Intake gasket anyway.

I hope my solution is very helpful and would like to know what you finally found as the problem.

On the 4.7L, the cam position sensor is located on the right cylinder head (thats the passenger side) toward the front below the valve cover gasket. Not on the front of the head but on the side where the exhaust manifold is attched at the forward end of the head. The crankshaft position sensor is located on the same side (right) but is at the opposite end of the engine between the bell housing and the block. The crankshaft position sensor can be replaced without removing the engine or transmission, it just looks tight. Also, on the crankshaft position sensor, it slides out of a rubber gromet. Here's a few pics to help.

Are you sure you have correct timing? its definetly a fule problem, if timing is good then turn your key to the on position and try to listin for the fule pump to prime. While the key is in on position go to fuel rail, there is a valve on fule rail called sharader valve. Get a small screw driver and press valve in to check if car has fule pressure. if pressure is present then it is incorrect timing or possible bad cam sensor.

If it is cranking with out turning over I would check the fuel pump and ignition relay, crank and cam sensors.
Basically you need to figure out if you have a spark issue or a fuel issue. (as long as you didn't have a serious overheating problem). One way to help you figure this out is by spraying in some starting fluid while cranking the engine. If it starts you have a fuel problem, if nothing then you have a spark problem (assuming you didn't blow the head gasket from overheating and was running normally before this happened).
Based on what you've already done here are my recommendations:
No spark: check ignition relay
No fuel: check fuel pump relay (aka shutoff relay, aka fuel pump shutoff relay), crank and cam position sensors, fuel filter.
There is also one other possibility, that the timing belt snapped. You would need to remove the timing cover to check this.

It may be the crankshaft sensor.Some cars use sensors that "watch" the crankshaft.When you turn over the car the sensor sees the crankshaft moving and tells the computer to send fuel,spark,etc. I am not real keen on your particular car but it sounds like this may be your problem.