ofg

I just recently tried to drive a 93 infiniti g20 back to Colorado from SLC Utah. Car ran fine in city, but started acting funny in Provo. It died when i pulled into a parking lot to park. Seemed to run fine before that. So, I went ahead and tried to go over soldier sumit,, big mistake. Higher I got, the less power it made, till finally I had to keep it in 3rd gear at about 4000 rpm to make it over the top. Any less rpm and it would start to stumble. Once over the top, I put it into 5th, and let the rpms drop,, sinse its now downhill,, and it just lost power and died. Starts right back up, but would not run for 30 seconds before dieing again. Sooooo, I rented a car hauler,, and towed it home. Havent run it yet after getting home. Oil is fine,, coolant is fine, no mixing of the 2 so I dont think its head gasket. Power seemed fine at first,, but it was down on power when I took off from provo. Funny thing is it starts very easy every time???? 160000 miles,, all stock. Looks like it wasnt maintained all that well because the engine is filthy dirty. Trans and clutch seem fine. All lights, radio and electricals work. I was gonna get a couple cans of degreaser, and clean up the engine before messing with it to fix. Any suggestions on where to start? BTW, I did search, and there were a ton of different threads,, and none with this same exact problem..Oh, and another thing,,, the temp gauge was reading normal all the way up the pass,, never blew steam,, no OBVIOUS indications of overheating. Last SE-R I had required a new fuel pump because it keept dumping at the most randome moments,, but it would require a days sit before starting again.