I think its an engine performance issue. Your 4.9 should be loafing along at 2500 RPM and it can't. I would start by checking and make sure your ignition and fuel systems are in working order because I do not think you have an issue with your final drive ratio..

 

My 1991 6 cylinder with 3.08 gear ratio is doing around 2,300 rpm at 60 mph in 5th gear and pulls strong. I agree with raski, something is wrong somewhere with your motor or fuel system.

 

Thank You everyone for the help. I took you all's advice and tested a few things. I ended up replacing Plugs, Wires, Ignition Rotor, and Distributor as well as the Fuel Pressure Regulator In the process of pulling wires I noticed my distributor was loose which i suspect was most of my problem as it would move in the engine. However I got it back together and it made a hell of a difference. Now it tries to spin "tire" and doesn't hesitate when I go to give it gas in 1-3 gear, but when i shift into 4 or 5/OD and step on the gas to get up to highway speeds I noticed that my RPMs will shoot up to around 4000 for a couple of seconds before they drop back down. Also while the RPMs are claiming for those few seconds it feels like the clutch is slipping but once the RPMs settle its goes fine. Is this normal? Or am I about to need new clutch and/or Transmission rebuilt?

 

Sounds to me like you need a new clutch. Eventually 5th will become unusable due to slip, and then 4th, and then 3rd, etc.

 

Will work on that next. Thank you.