When driving up hill I have a rattling sound at about 3000 rpm’s. It sounds like it’s coming from either the crankshaft or throttle body. But it does not do it in park. I do have leak at the crankshaft.

 

Give year, engine size and odometer in posts. I had to look up your year, 1994.
Also include a general assessment of the vehicle's overall condition. It helps communication.

Were it my vehicle I'd do the simplest and cheapest thing first.
Run premium gas in it.
Everyone says "Our 4.0l's run on regular-hurray hurray" but there's still spark advance (and a knock sensor) built into the engine.
See if premium fuel abates the pre-detonation (knocking).
If you buy the cheapest gas available you're leaving the door open for the kind of scum who put water in gas.
The ethanol in fuel actually pulls some water through the fuel system. Dishonest station owners are routinely found doing this.

Also remember, carbon builds up atop pistons and the top of the cylinder heads over time.
This carbon can heat up and contribute to pre-ignition on hotter days or when taxing the engine by going uphill.

You could also dose the fuel with a cleaner with PEA to 'possibly' clean the injectors. Do the PEA (Chevron Techron and other brands) before a stint of local driving.
I believe there's no way 30 years of carbon buildup within the cylinders can be remedied by a fuel additive.
There have been postings showing reduced carbon after some cleaners were used in lawn mower engines. You'd need a borescope to have any chance of seeing any improvement.
The cleaner would be for the injectors.