Car stalling on the highway!! Need some help.

[STL240SX]

Ok this is difficult to explain, but ill try my best. This doesnt happen all the time just at random bad times. Anyway ill be driving on the highway, just cruising at about 3400-3500 rpm, ill go to give it some gas, and then its like the car throws itself into nuetral, it will still be in gear, but i can rev the engine as i please for a few seconds, and then it starts to work again. Any ideas?? I thought at first maybe the clutch was slipping in fifth, but it doesnt always happen, so im at a loss. Maybe something in the ECU? If anyone has had this problem, or could possibly tell me what the hell is going on that would be great. Im definately open to any suggestions as well. thanks.

[019]

does it sound like the car is in neutral?
does it do that when you cruise at a higher rpm speed?

[Sil80girlie]

spark plugs? spark plug wires? I dunno, I just like to guess :)

It ONLY happens in 5th gear and at that RPM range? Anything else you notice when this happens?

[AKADriver]

That's definitely a damaged clutch.

[misnomer]

Is this a 5spd or automagic?

WHat you described really can't be anything forward of the flywheel. If it's feeling like it's kicking into neutral while you're cruising, it's probably the clutch dissengaging. It could be the car dropping into neutral, but then you'd have to put it back in gear yourself.

So yeah. Clutch.