My 91 jeep wrangler 2.4 engine and with 5 speed trans will not let me shift gears while driving i went to shift into third gear and the shifter sized up also the trans fluid was white like wood glue?

It sounds like when you bought it the previous owner or a shop that you had taken it to did what is called a "quick fix" in order to stop a noisy gearbox. I would imagine that the transmission is in dyer need of replacement or rebuilt.