2002 Windstar 170K miles 3.8L

I recently replaced the spark plugs, wire and fuel filter. My wife drove from Boise to Portland without any issues. Just in the last couple of days it has started to surge / hesitate during acceleration. It doesn't seems to miss or stumble when idling, however I do recall it stumble and the rpm fluctuate when at a stop light. This seems to have improved after the wires and plugs, however it is not cured.



I pulled the codes yesterday and got 171,174 and 306. So would an injector act this way that it seems fine at idle but then cause hestation or surging during acceleration?

Should I pursue the fuel pump, EGR or MAS?

thanks

 

The 171 & 174 codes signal a possible vacuum leak. Look for any vacuum hoses that might have come loose or cracked. You might want to carefully recheck the spark plug, wire and areas around the # 6 cyl. That should be the cylinder in the front on the driver's side. There could be more than one problem.
You could also check and clean the throttle butterfly.
You could look at the Mass air flow sensor wires and if they are dirty spray them with Mass Air Flow Sensor Cleaner Only!

 

i agree with hanky. I would add that the coilpacks don't last for ever. Consider replacing it as well.

 

Thanks everybody for your insights and tips. In my case the only code was P0306 with a flashing check engine light. The light flashing was frightening should the catalytic converter fail and its expense derail our budget. With your tips and some on YouTube, I changed the "6" cylinder plug and checked for ignition spark. I knew I'd take a powerful hit if it bit through my rubber glove. But, there was no spark clicking on the plug. With the high voltage over 10,000volts, I should have heard a click as it jumped the gap. Then in hand the wire didn't spark to ground either. So, I checked the coil pack by checking resistance between the primary side small terminals and also the Secondary output. The primary had uniform resistances but one pair of the secondary output had one unique reading. 2 pair showed 15,000 Ohm while the 3rd, including the 6 cylinder output, showed infinite resistance (open ckt.) Replacing the coil made the engine return to smooth running. I'll check back in a few days to say whether the Check Engine Light remains off. Thanks again very much. My budget could not withstand a shop repair - no joke paycheck to paycheck here again. I hope this helps another as you helped me.