I have a 1995 Nissan maxima se. I took the car to the shop because it wouldn't stay running. The code that came back was the mass air flow sensor was bad and the egr valve. Ok, I bought a sensor from a salvage yard that the people tested and it works just fine. Put the new sensor in and the car now runs. The problem that I'm having now is the car has a rough idle and it hesitates when accelerating....what could cause this problem? I done changed everything dealing with the codes. What do I need to check now?

 

Sounds like a vacuum leak dude!

 

I second the vacuum leak. Trace it down with an unlit propane torch or some carb cleaner?

 

did u reconnect all the air hoses??

 

Vacume leak is a good posibilty. When is the last time you've done a tune up? Changing plugs, wires, fuel filter and air filter could help aswell. Exessively pluged or dirty air filter could have contributed to the cause of your maf failure. Along with your tune up you could also clean the throttle body and maybe seafoam it. Weak coil(s) dont always throw a code and can contribute to hesitation aswell. In other words could be any number of things. You gotta do a little investigating but start with a good tune up if one hasnt been done for a long while and check for any cracked or leaking vacume hoses.