My automatic 2000 Ford Ranger with 155,000 miles act like it's gonna stall if i put light pressure on the accelerator, however if i press it normally it just accelerates and it doesn't feel unresponsive, i have the trouble codes P0102, and P0172.
1. Check your air filter to make sure it is clean
2. Chexk your fuel filter to make sure it isn't clogged
3. Check your catalytic converter(s) to make sure they aren't having issues or rattling inside
4. Pressure test your fuel pump
5. Run a bottle of fuel injector cleaner through the tank
Those would be some of my starting suggestions. Simple things first.
If you run those two codes through Google, P0102 is a voltage issue in the MAF, and P0172 is the oxygen sensors are telling the computer the exhaust is too rich. Get some MAF sensor cleaner, your MAF sensor out and give it a good spray down. Black stuff will probably come out. Also check your air filter while you're in there. Cleaning the throttle body with throttle body cleaner may help as well.
I would check for vacuum leaks. They will let unmetered air get into the engine and the O2 sensors will tell ithe ECU the exhaust is too lean, thus it will put more fuel in and trip the too rich code. Look for disconnected hoses, etc. Pushing hard on the gas dumps fuel into the engine, somewhat offsetting the excess air.
If those don't fix it, it could be your MAF. Get the original Motorcraft part, though. My Ranger's a year older than yours with 262.5K and the original MAF, so that's probably still good.
Also, find your MAF sensor and check the air hose from there to the intake.
Often, the old rubber hose develops cracks in the ribs (you may have to remove it to inspect) and causes stalling and stumbling.
