ym42

I started noticing a slight hesitation, I think it mostly happens when cold. When I press the accel. pedal, the car does not accelerate accordingly, but sort of waits a little and then starts to gain RPM faster ( starts more sluggishly and then goes back to normal, in other words ). It only lasts about 1 second. I got 58000 highway miles right now, original sparkplugs. Fuel filter is changed. But something tells me this is not the ignition... Any ideas?

Simon1

If you had a custom tune I would suggest looking there first. Things you could try is cleaning the throttle body, unhooking the battery, resetting the adapative memory. Those thing don't cost anything and can be related.

No mods on the motor?

300GT

+1 on cleaning the throttle body and/or MAF sensor. With that many miles that wouldn't be a bad place to start, assuming you don't already clean these things routinely.

One Bad Stang

ive got the same issue and i believe its definatly related to my tune. i have talked to brenspeed about it and they think its just because i'm in too low of a gear. in all reality, it happens after cruising for a minute or so and without lifting off the throtle, i will go to accellerate and it will sort of bog/accellerate slowly and then go back to normal. and like your problem, it only lasts for a second or two, but that will lose a race.

i can get arround this issue by lifting off and then smashing down the gas, but that is annoying to have to do that every time. it may have something to do with the way this tune is handling the heat in vegas. it has gotten worse as it has gotten hotter.

Nuke

If you guyz were mentioning that it happens on acceleration AFTER cruising at highway speeds, then I'd almost have to say that it's the fuel pump per the TSB. But with the miles some of you are reporting, I'm sure it would have reared it's ugly head much earlier.

+1 on the TB and MAF cleaning, then reset the adaptive learning for starters.

ym42

No mods at all. Seems to happen right after starting the car. I think it goes away later as I keep driving. Usually it feels like the car suddenly starts accelerating faster with no change in pedal input from me. And it obviously noticeable when accelerating ( not hard ). Can there be some more serious problem as with VCT for example? I have not done any throttle or sensor cleaning but the miles are all highway...

Nuke

Do the TB and MAF cleaning plus the adaptive learning reset to begin with as these won't cost any more than the cleaner. Troubleshoot after that if it continues.

One Bad Stang

i had that tsb done to my car even though it does not fall in the affected production range. i had a buddy at a dealer and he did it, but no fix.

Mr. Ugly

Change your fuel filter if you haven't already.

Could be restricted and delaying the initial increase in fuel flow. Especially if you can trick your car by lifting the throttle and flooring it.

Mr. Ugly

Oops... didn't catch that about your fuel filter.

How many miles on it?

They're good for maybe about 24k.

How about injectors? Run some cleaner through them?