I've got an '07 5 speed GT with 70K miles on it. I'm not hard on it, and literally nothing has broken. Lately I've noticed the engine missing a tiny bit on easy acceleration in 3rd thru 5th gears. For example, I'm cruising at 45 in 5th and lightly accelerate and I get an immediate miss before she starts to go faster. If I floor it, it doesn't happen. On hard acceleration, she still explodes in 1st and 2nd with no hesitation. She idles smoothly, and there are no check engine lights. By the way, I cleaned the MAF and throttle body about a year ago. Just hoping someone had similar symptoms and could provide a clue.

 

Never replaced the plugs I take it? I have yet to find a plug that actually lasts the 100K they all promise from the OEM. Generally speaking 30 to 60K is about the norm for copper to platinum/iridium plugs. Since you have the two piece plugs you'll want to look up the TSB for 4.6L engines. Like this one.

http://www.revbase.com/BBBMotor/TSb/...dPdf?id=142690

Many, including myself, have gone with CHampion 1 piece plugs PN 7989. I changed them when the car hit 10K to avoid breaking the OEM 2-piece at higher miles, had them in there until 70K (for 60K) and am now at 76K with zero problems on the first and now second set.

 

You are correct - original plugs still. I guess plugs could be a good starting point. Thanks for the info.

 

Another vote here for the one piece Champion plugs. I too am on my second set. Car runs like a bear. The thought of removing them doesn't keep me up at night.

 

there is an article I read somewhere on here or another forum about this issue, slight hesitation after pressing the gas pedal after cruising a distance. in the article, the issue was described as cavitation? I believe. something about the fuel in the tank having bubbles in it around the pickup from either vibration or something, that in turn caused a weak fuel mix just after pressing the gas pedal. if I set the cruise to a set mph for a bit then hit the gas to pass a car, my 05' has a very slight hesitation. it mostly happens on straight non-undulating terrain. if you slosh the gas around a bit, it tends not to happen. just my .02$ good luck

 

If I remember correctly, there was a TSB for what you are describing. I had my fuel pump replaced back when the car was still under warranty as per that TSB and I never had the issue again.

 

Most likely fuel pump, but a change of plugs is never a bad idea. I went with the oem ones again, just apply the motorcraft nickel grease and they won't stick. Tried the Champions and they sucked.

 

the champions are a good plug but are gapped wrong out of the box. lots of ppl have had good luck with them. my car likes the OEM motorcraft sp-514 so ill stick with those.

 

Also running the Champions here with no issues.

 

I gapped them, but they developed a misfire after a short time, went back to the autolite/motorcraft oem ones, problem gone.