Radomly hesitates, on highway, normal streets and sometimes at idle. starts right back up if it stalls but seems to do it only after the engine has been stopped and restarted.

Most likely it's you fuel pressure valve located on the fuel rail. Just unplug it and it just has one t25 screws that holds it on.

013 Idle Speed Problems PCM Test

007 Idle Speed Problems Scan Data for Idle

test don't guess .

hi i would try fuel injector cleaner product u add when u put gas if injector problem it will solve it if not its carbon build up on throttle body air fuel mixture is an issue also look into maf sensor mass air flow is there a check engine on if so could send u in proper direction gasing up a tank of premium super 91 octane and up will help clean out minor issues danny

Plug the vacuum line you unplugged and the idle should come back. Change your air filter and the map sensor. check for correct coolant level and replace the coolant temp. sensor. This sensor affects cold starting and idle through the ECU (open loop mode, rich fuel mapping and 1200 rpm idle) It should go to closed loop mode in the ECU once engine warm up is achieved ( lean fuel mapping and normal 900 rpm idle). Do not unplug anything else till you perform an OBDII scan of the stored fault history

the egr valve could be sticking causing this issue put a vacuum gauge on the egr valve to draw a vacuum then release it to see if it sticks

check for codes. If no codes are stored then maybe the idle air control valve is bad, or the air cleaner clamps are loose.. If the clamps were loose or a vacuum hose fell off you should have a code stored. If the IAC is bad it usually will not set a code.

Throttle body, IAC or EGR valve.

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

maybe try replaceing the ingnition modual. that part can do a lot of weird things to these cars. its located inside the distributor cap, really easy to do. about $40 and 10 mins or less. sometimes as they start to fail they do odd things sometimes but not always

Check the air filter hose. My '99 Protege was idling rough and would sometimes shut off. The air filter hose was cracked half way around. I replaced it (easy just loosen two hose clamps and pull out the sensor) and the car is running fine.