I have a 02 sentra gxe 1.8L it idles real rough and when step down on the gas whether in park or drive will either stall or rev up a little and start spitting and sputtering, the only code coming up is the maf sensor to high voltage, the maf sensor has been replaced along with the ecm. the shops have told me the fuel pressure is fine so now theyre ay a lost

SOURCE: 2002 NISSAN SENTRA GXE 1.8 POOR IDLE LACKS POWER IDLE FLUCTUATES BETWEEN 1800 TO 1100 RPM

Check for vaccume leaks and also you PCV valve. check the hose too. Visually inspect every vaccume hose you can find. Sounds like a leak .

SOURCE: 2002 nissan sentra gxe computer

buy a used unit from the junk yard.

SOURCE: 2002 Nissan Sentra Loses Power

SERVICE IT .....OIL PLUGS, AIR ,FUEL AND OIL FILTERS GET TROTTLE SENCOR AND THE MASS AIR FLOW SENCOR CHECKED

SOURCE: Step by step on how to replace front wheel bearing

Raise vehicle, remove wheel, remove brake caliper, remove brake rotor remove steering knuckle by disconnecting the tie rod, ball joint, and strut. press out hub, remove snap rings press out bearing. Reassemble in reverse order.

SOURCE: 1999 Nissan Sentra GXE timing belt/chain maintenance

good day Sir, your nissan sentra 1999 gxe have a timing chain this is some tips for your routine maintenance.
Replace engine oil
Replace engine oil filter i