I have a 2003 Ford Focus ZX3 and it will sometimes start to lose rpms like a seesaw and if not given more throttle will die completely. The Engine just shuts off, it does it completely at random one day it will work fine the other day. Sometimes it will work early day and die/shutoff later. The car after it dies will start right back up but sometimes will still be losing rpms or die if not given gas. I am really confused... What is wrong please help.

. Change the spark plugs with the same Motorcraft plugs that came in the car, if they have not been changed in 50,000 miles.

. Change the fuel filter, if it has not been changed in 30,000 miles.

. Perform the tests below:

https://www.askmehelpdesk.com/cars-t...ml#post2123675

It's possible either the Crankshaft Position Sensor or Camshaft Position Sensor is bad, if the problem persists.

What is the maintenance history for this car?
Have you had the idle control ports or throttle body cleaned?
Any trouble codes? Check engine light on?
You may want to check with your local dealer to see if there's any software updates for your car that may provide a fix. It's worth a call.

**edit** I see there is a drivability update available but your car may already have that one

Check engine light is never on, only light that comes on is the multi function light (Exlamation mark with squigglys around it) when its rpms start jumping. Fuel Filter was replaced recently spark plugs probably not.

Quote:

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Originally Posted by Atroxica

Check engine light is never on, only light that comes on is the multi function light (Exlamation mark with squigglys around it) when its rpms start jumping. Fuel Filter was replaced recently spark plugs probly not.

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That's called the Powertrain Warning Lamp. That lamp serves the same function as the "check engine light" but your manufacturer calls it something else.
Have the code(s) read and diagnosed. You'll have found important clues as to the changes in engine speed.

I ran the diagnosis scan on the computer we have in auto class. Here's what came up:
P1270 Engine RPM/Veh Speed Limit Reached
B1600 PATS Ignition key transponder Signal not received
B1602 PATS Received wrong format Key Code

My friend said it could be the sensor on the cold air intake on it, but not sure. He said to take it off after it dies, and it shouldn't die anymore. I'm going to try it and post what happens. Thanks everyone