2.7 stumbles like its starving for fuel.

MY fiancee and I just bought a 2010 toyota tacoma access cab prerunner, About seven months ago. Not long after we bought it I noticed it would start stumbling in second gear like it wasnt getting enough fuel and I would have to shift up to third to get it to stop. Ive scoured the internet but couldn't find any info. I don't believe its a dirty fuel filter, because it only does it in between 2nd an 3rd gear, Im leaning towards a dirty Maf sensor. I also don't believe it to be my spark plugs, But then again I'm no mechanic. It's my daily driver and i have to have it for the 140 mile round trip to work. Any suggestions? The truck only has 61,000 miles on it.

 

I'd run a tank of fuel system cleaner through it for a week (to me it sounds like a fuel injector is sticking open) then drain the oil (let it drain overnight if possible) and replace the spark plugs. Check all the vacuum lines and air intake hoses are tight. Cleaning the maf is good, too. Good luck.

 

Red Line Oil SI‑1 from O'Reilly Auto Parts has made my vehicles run a lot better.

 

I'll try this first, I've ran stp fuel system cleaner through it. And the regular old stp gas treatment. Still did it, but wasn't as often.

 

Check or replace the spark plugs, they are due at 60,000 anyway if I'm not mistaken.

 

For reference:

I went to BITOG when I was looking into it, and no one ever says anything bad about it. While many others are recommended also what makes me a user of it is the price and availability.

If that doesn't help I don't think anyone has mentioned maybe having some water in the gas. Dry it up with HEET.

Those made a huge difference in another vehicle I maintain. The SI-1 is a regular additive now in my Tacoma though.

If it doesn't then other advice is more relative.

 

Update:
I did a complete tune-up this weekend, Switched it over to synthetic oil, brand new oil filter, air filter, And brand new NGK Iridium spark plugs. My old plugs looked pretty damn good, Also no change it still does it. Maybe a dirty MAF? Im running out of ideas, and patience. I couldn't find the SI-1 additive any of the parts stores around here and the mouthbreather's behind the counter couldn't help me either. Ill order it in the next two weeks, and report back. Sorry to keep bothering, But This is an expensive investment and I'm getting aggravated.

 

According to their website it's available here:

O'Reilly Auto Parts
607 North Pine Street
DeRidder, LA 70634
(337) 463-7727

O'Reilly Auto Parts
1905 South 5th Street
Leesville, LA 71446
(337) 238-5488

http://www.oreillyauto.com/site/c/d...oap?ck=Search_N0404_-1_867&pt=N0404&ppt=C0126

 

Check all of the vacuum hoses. Sounds to me like there's an air leak.

Also try this:

Disconnect the cable on the negative battery terminal for around 5 minutes, and then reconnect it. This allows your ECU to relearn its operating parameters.

 

Stumbling like it's starving for fuel in 2nd, but runs fine in 3rd, sounds to me like you're bouncing off the rev limiter.

Just what are your RPMs when it starts "stumbling"?

 

Sometimes the most simple explanation is the right one...

 

Been there a dozen times on the Vulcan. Not so much with the louder pipes, but when I put a set of quieter pipes on it, I was always hitting it getting on the freeway.

 

My rpm's aren't high at all, I would know if I was bouncing off the rev limiter. It's a problem tht only pops up from time time. Not speed or rpm related, I don't drive my vehicles like that.

 

My truck is a 1st gen but has the 2.7L. I had issues similar but it finally threw a code for the throttle position sensor.