I've had my 93 SE 5-speed at some guy's shop for 3 weeks now, and he finally told me that he can't figure out what the problem is. I bought it with 130k miles on it, and the next day, something started to heat up and whenever I changed gears it revved up to about 5k, and then back down. It gradually slowed down until all it would do was rev in any gear. They towed it back, and had a guy look at it. He replaced the clutch (what he thought was the problem) and it did it again the next day. He accused me of abusing it, but after about a week he realized that something else was causing the problem. He had to replace the clutch again, machined the flywheel, and did a few other things... took it out on the road and it did it again to him. He can't figure out what the problem is, and he is now talking to Nissan, but that's not getting anywhere. Can everyone please throw in their 2 cents to see if I can try to get it going again. What could be causing this?

 

Either the throttle plate is not completly closing, air leak in a hose or Throttle Position Switch.

 

you're saying you had the car in gear, revved the engine, and the car wouldn't move- just the engine would rev up?

if so, then you've obviously got a bad clutch/clutch system.
It could possibly be the LSD in the tranny, but I seriously doubt it would cause that.
have they checked the throwout bearing and the hydraulic clutch system? if they haven't, then they're freaking morons and need to be slapped. It sounds to me like there's maybe a problem with the throwout bearing and hydraulics. have them bleed the system there and see what happens.

since you talked about heat, that could cause it. boiling the hydraulic fluid creates air bubbles in the lines which will cause this problem.
good luck.

 

Well from what I've been told, they have replaced the clutch twice, once from the first time it died, and one from the second time. I'm fairly certain that they replaced/repaired anything that was clutch-related, but it's not my mechanic, it's the dealership's mechanic, which makes me weary.