Gear shifting noise

Hello. It seems your vehicle's transmission has to be rebuilt/replaced. Any automatic transmission that won't 'shift' from 1st gear into 2nd or 3rd gear has a 'worn' slave cylinder that 'slides' gears one way or another. 1st gear works yet 2nd and 3rd don't. Good luck and keep me informed; if you want to.

If it grinds when trying to shift, it is the synchronizers. Rebuild. If it pops out of gear. there is a plastic part at the top of the transmission that wears out. It fits around the ball of the shifter. It is two pieces. You'll have to remove the floor plate and pull it up to access the bolts to remove the shifter and replace those plastic pieces.

4th gear is not a gear as such but a coulping of the input and out put shafts to make a complete shaft
If there is a problem moving this coupling it indicates a syncro ring problem or spigot bearing failure in the end of the input shaft
either way it amounts to a gear box removal and pull down for repairs.

don't shift into 1st until stopped and 10mph or less is your down shift range to 2nd gear from 3rd

The 3rd Gear Synchro is worn or damaged, which is why it grinds when you try to upshift or downshift into 3rd gear. When it goes out completely you will have a very hard time shifting into 3rd gear, since the Synchro lines up the gears to make shifts smooth and easy.

Your pressure plate must be weak and about to let go.

What is happening to you is worn out sincronizers in you transmission. They are used to mesh the gears between shifts. They are made of brass and wear out easily on the 2nd gen cars. It grinds normally going into 2nd gear and into 3rd if its really worn. If you want a stronger transmission buy the 93 and up 3rd gen tranny. It is an upgraded transmission with dual sincros. Yours does need rebuilt. Or you can find one on the MR2 board for a good price used. I prchased a 93 trans for $1000. An older one will be about 200. Also it depends if its turbo, lsd or not. Good luck!

Bad syncro for third gear. Sorry, but you aren't fixing this one yourself, unless you replace the transmission yourself.

check shift fork adjustment. make sure you bleed the slave cylinder.also check shift cable adjustment.

STOP Downshifting!
STOP Forcing gear change, watch the Engine RPMs and shift accordingly, HOMBRE's are as good as the operator's. Hombre's have dash shift indicators which illuminate when it's time to 'shift' and not before, This has nothing to do with gear oil either. If you've drained it, you best fill it immediately and make sure it's ample level. The heat these gears sustain in is inceredible, cooling lubricant is essential. Here's a tip, while engine is OFF, ignition key is engaged, dash is illuminated, depress clutch peddle, keep it depressed and walk through all gears with gear shift, shifting should be smooth and unpeded, including reverse. If resistance is experienced at one or more gears, gear alignment is off as a result of inproper gear shifting while driving. Continue to drive vehicle just shift slower until clutch needs replacement then do an entire drive shaft upgrade. It worth it, it's great truck.