Need diagnosis for sudden 5 sp. man. trans. problem

Car is a 1988 Mustang lx 5.0 Basically, my car was running pretty good up until I was on the highway going about 70 mph...I dropped it into 3rd from 5th and floored it until redline..over 100 mph. I then took it out of gear and tried to put it in 5th from 3rd..Wouldn't go. Came to a stop, and had a hell of a time getting it back in 1st. Now, when I come to a stop at idle, the car vibrates/shakes which it didn't used to. It is also now always difficult to shift into any gear.

Also, when taking off normally from first gear now, the car bucks more than it used to. It always has a little since it has 2.73 gears, but now it's more pronounced. Also while cruising giving it light gas, it starts to buck lightly and randomly. I had felt this before and thought it was a slight missfire, but now it does it even more. Just wondering what this most likely could be. Any help is greatly appreciated.

Of note, I just got the car 6 months ago and it has about 157,000 miles on it, of which I've only put on about 1,500. For the drivetrain (clutch, tranny etc.) I don't know what's stock or not...The clutch peddle has always been a bit stiff but I've never had problems shifting. I always thought maybe it had an aftermarket clutch.

You may have multiple problems. To start with, the vibration while idling sounds like your harmonic balancer. I just replaced one on my wife's '93 GT with 167k miles on it. I had never had one go out before but when I looked at it, I could see the counterwieght had seperated from the inner half of the balancer and was trying to walk up the pully. If it's your balancer park it until you fix it. If you eat up that keyway you will find yourself replacing your crankshaft. Didn't happen to me, but have seen it with two other vehicles recently. If you are mechanically inclined you can change it yourself, but when I did it it got envolved: balancer, front seal, (had to take the timing chain cover off to get front seal) then since I had the water pump off to get to the timing chain cover, figured I may as well replace the water pump since it can be a pain and they only run around $27.00. The good news is that my knuckles have finally healed up after three weeks.

Back to you. The rough engagement and grabbing sounds like your pressure plate is worn and/or has broken tongs. Do you hear any squeeking from your tranny in idle? Could be your throw-out bearing is broke, or the fork. You may want to drop the tranny and have a look. Get 'er fixed soon so you can get back to keeping those highway folks in their place. :naughty: we all know why our stangs scream at 4grand around 100mph in third. You know if you get it over that hump and find the other two gears you can really show them up around 138. (not recommended on highways, dirt roads, or parking lots.)