new to me used 05 tacoma with a few questions

this is an 05 access cab 4x4 4.0 6 speed with 100k with no mods to speak of. there is a surge when i accelerate strongly. I don't know if surge is the right word but the truck will pause for a 1/2 sec or so then accelerate smoothly, then pause breifly then accelerate smoothly. does this in most gears but doesn't do it if i accelerate gently. also will not do it in cruise control unless going up a long hill and the truck needs more gas to keep it cruising at that speed. drives very smooth at a steady speed. rpms do not drop during the pause.

also, idle will dip down to 500ish get a little rough then climb back to 800ish at a stand still after warmed up. No other things on like the air conditioner. Is this normal. its not bad just noticable.

the previous owner said he replaced the 02 sensor, TPS, MAF, changed the oil and filter with royal purple, tranny and diff fluids just changed. he also said the acceleration surge was always there, changing all the sensors didn't change anything. I ran a bottle of sea foam through the gas tank. It had a bit of a rough idle to it to begin with so I sea foamed it, worked well but then the idle flucuation began.

any thoughs greatly appreciated.

 

Welcome. Tried changing the fuel filter? I'm not sure if there's one on the fuel pump either but it might need changing too. I've read a couple other threads with this issue but they were first gen issues.

 

When was the last time a tune up was done?
I'd change the plugs and air filter and reset the computer. Sea foam may have moved all of the contaminants from the intake to the plugs... The engine will probably have idle issues for a while after resetting the computer, but will smooth out after the first 20 or so miles while it learns. Start with the simple cheap stuff would be my suggestion.

 

I think the fuel filter is in the gas tank and you have to drop the tank to get to the filter. I'm not 100% sure of this but I also read you shouldn't let the fuel tank get to low because of this. Someone correct me if I'm wrong.

 

You are right. But there is 2 fuel filters I thought, one by drivers side under carriage and one in the pump its self.

 

The fuel filter on the driver side frame rail is only on the first gens. Second gen is in the tank/fuel pump.

 

Absolutly, i probably won't send alot of money tracking this down. I can live with it, just though this might have pop up before. Original owner said he changed the plugs about 10,000 miles ago. Dont know abut the air filter, i would guess its the dry filter. It was a k&n air fliter, i could see the oils covering the MAF sensor causing some issures.The truck definately had the engine surge before the seafoam, i just thought it was worth a shot.
I'm wondering if cleaning the throttle body would help, although the truck isn't sluggish or have poor throttle response, it just has the surging acceleration and a slightly fluctuating idle.

 

My 05' with 130K does the same thing. Has new plugs, clean air filter, syn diff. fluids, cleaned the throttle body, etc.. I hope someone on here figures out what it is. I can live with it but I wish it didn't happen.

 

Did you clean the MAF when you cleaned the throttle body?
Have you checked for codes?
I'm not sure if the O2 sensors have a recommended replacement mileage.

 

An easier way would to unbolt the bed and tail lights and slide it back a foot and pop off the top of the gas tank opening its way simpler then dropping the whole tank but it only works if you have the 6'ft bed either in AC or DC...of course you have to have a few friends to slide the bed but its so worth it....I changed my stock pump on a 05 to a walbro when I had it