92' 5peed problem

I have a problem with the reverse. When I go to shift into reverse, it feels like there is no slot to shift into, its like there isnt even a reverse at all.

I was driving down the freeway and shifted into 5th and after about 5 seconds it popped out and make that loud grinding sound, and ever since my reverse hasnt worked. After about 20 minutes of messing with it, i found that if i hold it down like i am going to shift and release the cluth and press the gas it will let me slid into reverse but it wont engage untill a good bit of grinding.

After it engages, my shifter is literally STUCK in the reverse postion and i have to use my whole body weight to push it back out, all of my other gears are fine.

Any thoughts on the problem?

Miles=142,225
Non v-tec

Any help would be greatly appreciated.

When is the last time you had your tranny fluid changed?

I have no idea, I just bought the car a month ago and already a whole host of problems have arisn.

The transmission problem has settled it self, i went out the next morning to leave for work ,and it shifted into reverse with no problem.

Also the idle is very rough, around 550 rpm, i checked the plugs and they have oil around the threads but not on the electrode. The plugs are also very dark, too much build up id guess, i figure the car is going to need a good tune up anyhow.