2001 elantra cutting out?

My elantra will run excellently, then bam! it loses power as if I left off the gas. I pump it and it will backfire then go again. It does not shut off however, just idles down. It has all, every sensor replaced! Everyone! New coilpak,plugs wires.charcoal canister good both purge valves good! New pcv valve. No leaks in intake, or head. Timing belt new. Fuel pump,and filter new. Runs great sometimes, so as mechanical crap does not go bad then fix itself off, and on it cannot be mechanical! It has been to three garages, they can't find anything! Cat converter good not clogged! Keeps putting up codes that say items already replaced are faulty. Service eng. Light not on. All wires, and plugs good, no problems with cranksensor, O2 sensors new! I think the main computer is going crazy, what else is there? Any ideas? If I get a new ecm, do I have to go to.a dealership to have it programmed, yes or no! Thanks!

?2014-04-03T18:00:11Z

Favorite Answer

Wow, you have done alot to find this problem.
That last thing I can recommend it replace the fuel pressure valve on the end of the fuel rail - it may not be working properly and allowing to much gas to return to the gas tank, causing low fuel rail pressure which will affect injection of fuel into the cylinders.
Hope this helps and you find your problem.

?2014-04-03T21:10:50Z

try asking on AutoMechanics.com also
live tech there to answer and help with your repair.
upload your repair photos, videos, live chat with a tech about your repair. Great site with access to every repair manual for every vehicle and access to certified dealer techs for every make and model

Really ?2014-04-03T20:55:36Z

Everything replaced... my guess would be bad gas. Maybe water in it?

?2014-04-03T21:01:38Z

you need to replace your engine. go to hyundai and buy a new v6 engine and replace it