My daughter has a 1995 altima. When you start it when it is cold, it runs great. After it warms up , 5 minutes or so, it starts missing and yesterday, it left her stranded. It died and wouldnt start. After it cooled off some, it started right up until it got warm again. We bought a wrecked altima that ran really good, and started replacing parts. We have replaced almost all sensors with no improvement. At first, we were getting a p1400 code, we replaced the egr solenoid and the code went away. We arent getting any codes now, but it still is running bad.
We have checked fuel pressure, it is ok, we replaced fuel filter, plugs, nothing has helped. Any suggestions as to what would cause one to run like this with no trouble codes.

Idle Air Control Valve, bad coolant temp sensor, spark plugs not gapped properly, bad air filter, plugged exhaust/cat, bad ecu. Bad MAF?

hows the coolant? did you replace the spark plug wires with the plugs? make sure your spark plug wires are not crossed or touching anything hot like the headers or something like that.

QR25DE nailed it...coolant sensor is #1, that sensor keeps the idle up but a bad sensor is likely.