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Faulty Acceleration

03 Mazda Protege
Sometimes when leaving a stop sign, it’s like the car forgets how to accelerate. It never stalls out, just feels like it’s going to. If you shift it into neutral real quick and back to drive, problem solved. Accelerates fine. Otherwise you can feather the gas pedal, or just mash it to the floor - eventually it crawls forward and then at a certain point, it drives flawlessly.
Other times - not the slightest hesitation - just zips right along.
I’ve replaced the Mass Air Flow Sensor, Throttle Position Sensor, Fuel Injection Pressure Regulator and now also the Fuel Injection Pressure Damper. Still no change. Any other ideas?

I had similar symptoms when my spark plugs were really overdue for change.
How long since you replaced yours?
Seem like you already replaced a lot of parts although

Get a better diagnosis before anything. If it were an engine problem you would probably have a check engine light on or even flashing. Transmission a more likely suspect.

I’m thinking the transmission is ok. It works great all the other times. No problems at all. (Time will tell)

Thanks. I’ll give that a try.

If the engine doesn’t rev up (rpms increase) when this no-to-slow acceleration thing happens, probably not an internal transmission problem. But it could be the transmission range selector sensor failure, since fiddling with the gear shift lever seems to help. It sounds like it is getting too lean, and if the computer thinks it is in one gear but it is really in another, that could cause such a symptom. Another idea, if the gear selected by whatever selects it (transmission control module presumably) is too high for the vehicle speed and engine rpm, that could lug the engine & this could result. An experienced tech would be able to identify if that was happening by a test drive.

You’ve got most of the parts that affect the startup/acceleration replaced better take it to a trusted or top mechanic for better diagnosis.