Transmission issues.
 

New to 5-speeds, I just picked up a 86 4runner, 22RE, 5speed, was shifting fine until tonight, now its very hard to get into any gear. Shifts fine when engine isnt running, just did a fluid change last week. Any help or advice would be very appreciated.

clutch hydraulics unhappy, guaranteed. The trick is to find which of the two pieces are unhappy and why.

Check the fluid level (looks like brake reservoir bolted directly to the firewall, no booster) and check to see if it's wet behind the clutch/brake pedals (behind the carpeting).

If that's the problem, the good news is that it's relatively cheap to buy replacement hardware, the bad news is it's a PITA to install yourself if you don't have a well-equipped garage (air compressor, basically).

Any play in the pedal? Maybe the clutch went out? What fluid did you put in it? If you put gl5 in, take it out, its too slippery for the syncros. Put in GL4

I put in Castrol gear oil 80W90.

So I've been doing some reading, is there really that much of a difference between GL5 and GL4? Would it actually cause it to not shift properly within the run of a few days?

So it looks like this is the issue, the reservoir was empty. And it is leaking behind the pedals. If I start it in gear is starts to stall out. So my next question is how do I go about fixing this.

Thanks for your help.

Do a quick search in this board for "replace clutch master" and "bench bleed", there are some write-ups that will exceed what I can tell you (since I've never done it on my yota... yet).

Basically you'll need to swap out the hardware and then bleed the system. Bench bleeding will make the final bleed easier, but it's still a booger.