Ok i have a 97 max at ill try to keep this short problem started as hard start then went to bad idle to bogging and stalling and sometimes ran great went to diagnostic guy he says my knock sensor and iac and o2 1 bank 1 bad replaced all same problems go back he says ecu bad replaced same problem go to another place no codes he says its main cat put straight pipe same problem next guy says dirty throttle body cleans it....but while cleaning breaks maf housing by the metal screen i had cone filter attached with screws to make it round all cracked....he says no problem sticks a piece of some kinda screen shoves my cone filter on then backs out the screw on iac brings idle up car runs better but now power loss mostly low end is anybody left that cares and knows what they are doing hope for some luck on here....thx thanks for the answers i feel the problem is in the the maf maybe it has to have factory screen....also no main cat no codes i have heard some maximas these yrs will not throw a code or does this mean this ecu is bad....

 

If it doesn't have any power, maybe the screen he shoved in there is restricting air flow, if you're running an air filter, since he already broke the screen that was made into it, i'd just take the one he shoved in it out and see if that changes anything. I know your pain though, I have a 96 that's been nickel and diming me to death all to find out it has a burnt valve.

Have you went and had the codes checked by chance? If you have an auto parts store near you, they will usually check it and give you the diagnostic codes free of charge.

 

You should not be throwing parts at your car in order to get it fixed. It takes proper diagnosis to find the actual cause. Not an "oh this should fix that" type diagnosis. Should being the keyword.

I personally fix my own car because I enjoy it, I know it will get done right, and I have little trust in mechanic's (I know all are not out to get you though). I started out knowing absolutely nothing about my car until I started reading threads on this forum and doing the work myself. Take the time to do research on your problem because I can guarantee you that you weren't the only one to have the issue.

 

If you had a clogged cat, there is a good chance too much fuel from one or more leaking injectors is the root cause. Some time ago, I spent a bunch of time and money chasing issues that started with two leaking injectors.

If you can find a knowledgeable mechanic to run a fuel pressure test, it will tell you if fuel is leaking past the injector o-rings when the engine is off and the system is under pressure. Unfortunately, if you are dealing with "parts changers" then they won't have a clue how to perform injector leak testing on a 4th gen or be willing to take the time to learn.

 

Check for any pending codes that havent tripped the CEL. Knock sensor is usually a "ghost" code that shows up with other codes, although it can go bad which will pull backing timing, however it never triggers the CEL by itself.