I have a Mazda Protege 5 2003. While driving if you accelerate rapidly the engine bucks around 3500 to 4000 RPM. It absolutely won't go past 4000 and does this weird aggressive jerking thing where it jumps back and forth between 3500 -4000 RPM as long as you are pushing the accelerator hard. If you ease off the gas engine goes to normal operation. Also I if I accelerate slowly I can still get the vehicle to a highway speeds no problem. When the issue happens it doesn't feel like stall where the engine is being choked and might die or anything like that. While parked the engine revs to max rpm if desired. Intermittent P0171 code too with rough idle. Please help.


PROBLEM FIXED:

Let's just say there were many problems found with a lengthy list of parts changed not necessarily in the order mentioned. Among the first things replaced was the MAF to address the P0171 when the O2 sensors didn't fix it. I also found some vacuum leaks (intake hose), and that the valve cover was loose causing oil to leak down sides of engine and gum up some other parts like my injectors. So I replaced the valve cover gasket and put in new injectors, fuel pump, cleaned the egr valve, replaced the idle air control, swapped the cam/crank shaft sensors, new plugs/wires. At this point the idle was very smooth but the engine couldn't power over 4,000 rpm while accelerating the vehicle. Changed the throttle position sensor, then turbine speed sensor on Transmission...no luck either one.

At this point, I finally invested in a diagnostic tool and checked the MAF PID I found the the MAF was only showing 0.22lbs/min with a pretty slow response and steep drop off to zero at 3500-4000rpm while driving. This was the last thing I expected because I replaced the part from the start. Moral of the story...don't buy the $40 MAF get a decent one. Second go around I paid $160 for one with a lifetime limited warranty. I also bought some cheap 02 sensors from Amazon that didn't last long either until I put in some decent Bosch sensors. Sometimes cheap parts work sometimes they are trash and create more problems. With the new new MAF I immediately saw a difference, getting about 0.77lbs/min at idle and expected climb with acceleration and no drop off. Problem fixed and more.

Lastly, the FIXD brand OBD reader is almost worthless unless you subscribe to premium diagnostics. OBD Link MX+ is great