That 90 should only go down a couple of inches and connects to the oil cooler, but you want to then follow the oil cooler and disconnect the hose on the bottom of the oil cooler to feel for any large pieces of debris. It's not a lot of fun to get to.

To back flush, you can just remove the hose from the oil cooler (as you stated) and put the garden hose (wrapped with a rap) on the top of the oil cooler, then turn the water on.
By the way that looks like a newer 7.4l motor.

Yes it is a VI mpi.... Like it alot and very clean buy getting hot haha

28eliminator pic shows the cooler good its the vertical cylinder. On your motor its right behind idler pulley. Just flush as 28eliminator says and see if that's were the problem is coming from.

Curious at what temp does the alarm go off at?

Around 200*

Probably would not be a bad thing for the OP to take the diagrams on post #27 & familiarize himself with the components so he knows what is what & where it is for future reference. Just a thought. Randy

You do need to make sure that there is no blockage in any of the hoses your checking, but...
I have had the hose connecting the lower unit and it's pick up to the outside of the transom crack and allow air in and lose suction.
You may want to check that if none of this remedies your overheating. Trim the outdrive all the way up and inspect out there.

Unless of course you have water pick ups on the hull or somewhere other than on the lower.