99 Maxima no power under load and no dtcs

[KMA88]

I have a 99 Max 3.0l 5 speed that i can not figure out what the problem is. The car starts right up and idles fine and in neutral, it revs up without hesitation. When i drive it and try to put it under a load of about 50% or more it starts to stumble to the point where i cant drive it. The check engine light does not flash while it acts like this and this is no codes stored. I have replaced the coils with used nissan coils, new plugs and the front crank sensor has been recently replaced. I have checked the MAF sensor output and it is in range. Im at a loss and need help

[maxhopper]

I would check fuel pressure, and also see if the converter might be stopped up.

[KMA88]

I checked the fuel pressure and it's at 35 psi. The converter was recently installed but I'll check it out just in case

[loystock]

The fuel pressure is very good. Check for intake exhaust leak. MAF sensor test with DVM is inconclusive. Best way to check MAF sensor is with oscilloscope which very few of us have.

It's possible the MAF sensor is dirty or failing. And the problem is a dirty/failing MAF sensor will not necessarily trigger a fault code. So disconnect the MAF sensor and start the car. The CEL will come on (most likely P0100) and the car will be in 'limp mode' (RPM limited to <3000) but you should be able to drive the car w/o stalling. If Ok, then the MAF sensor or related cable/plug is dirty/failing. Please note that this is only for troubleshooting and the car should not be driven in limp mode for extended period (spark plugs and injectors firing simultaneously, not in sequence).

[KMA88]

I have replaced the maf sensor with no help. I ran some fuel system cleaner and it helped a little but not much.

[NutriaforBreakfast]

Just a guess-try and see if the throttle position sensor is working

[KMA88]

I checked the throttle position sensor and it is in range with no dead spots from idle to wot. The throttle position switch which is part of the same sensor is reading no continuity when the throttle is open or closed. Could this be the cause?

[NutriaforBreakfast]

http://www.nicoclub.com/FSM/maxima/1999/EC.pdf

[NutriaforBreakfast]

page 152 for throttle position sensor in fsm

[KMA88]

I found the problem. The front bank pre cat fell apart and was blocking the rear cat