@002 Protge 5. Very low idle and kinda dies out when driving. Put new plugs in it and still the same? Sometimes stalls at stop lights?

This sounds like the idle control valve or stepper motor as it's sometimes called needing a good clean out or replacement. When faulty this would cause all the symptoms you are describing.

an 03 has a gen 2 OBD that stores faults (not all faults trip the ck engine light) i would start there by doing a download (all faults)with a code ck'er , could be something as simple as an idle adjustemnt or maybe a vac line got broken/left off when doing the plugs/wire change , happens!!!

Check the idle fuel pressure. Load the electrical with headlights and heater defrost etc and see if problem gets worse. Attempt again with all accessories off. Could be fuel pump is getting low voltage at idle or fuel pump is failing. Bad fuel pump would definitely be a problem high fuel demand. Check vacuum line between pressure regulator to intake manifold.

Check for a air leak in the intake manifold. Gasket/hose etc. The P0171/P0174 is an indication that not enough fuel or tow much air. You can sometimes hear the air leak during idle.


Best solution is to use a graphic capable scan tool and watch the fueling trim/idle.

The idle air control valve job is to maintain a target idle,

Here is the common cause of surges, stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

You may have a bad fuel pump sock or you may have a plugged catilatic converter, does the truck take a long time to start after it stalls out?

this is your problem:

Here are the most common causes of surges, stalls at stops, low erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake

TRY THIS AND LET ME KNOW IF IT CORRECTS YOUR PROBLEM
Here is the most common cause of surges and stalls at stops and low erratic idle speed and rough idle, it is the idle speed control air-bypass valve and throttle valve (IAC for short), they get full of gunk over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake

Here is the most common cause of surges and stalls and low idle rough idle, it is the idle speed control air-bypass valve and throttle valve (IAC for short), they get full of gunk over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

have you ever had the injectors checked. if not try runing some fuel injection cleaners through it and see if that works