I bought my 05 Super Cab Lariat 4x4 from Carmax OKC and it developed a bad hesitation when accelerating between 3K rpm to red line. Took it in, explained the problem, then called me back later that day and said they will be replacing all the 2 piece spark plugs for starters to see if that helps.

In the back of my mind on the phone I was thinking **** YES! 05 spark plug change for free?!? LOVE Carmax! So far they did my cam phasers and now the plugs! All the big ticket, *** pain items covered! now hopefully the plug change fixes the hesitation upon acceleration. But I think its lacking fuel, not spark. And I read about some folks having injector issues.

Either way, they are fronting the bill for the repairs!

And here's a Pic of said truck for no reason...

 

If you think it's lacking fuel then it might be the fuel pump driver module. Not that I'm an expert on that by any means I just notice that that is a reoccurring thing on these forums.

 

^^x2. It's worth a look. And its easy to check.

 

Makes sense but luckily for me, the trouble shooting is carmax's burdon. I love their customer service policy!