Surging while driving! Driving me crazy!

I have a 2003 Tacoma with the 3.4 that has 152k. I have been noticing this surging while driving. It acts like the gas pressure drops then picks right back up, however it is very noticeable. I just changed the fuel filter about 15k ago, but just recently started noticing this surge. It does not happen all the time, but it is consistent almost every time I drive. I went to the dealer and they can not find anything wrong. But, I know different and it is driving me crazy. I have thought about the Cat starting to clog, or fuel pump maybe starting to go? Anyone with any suggestions would greatly be appreciated. If I can not do it myself, maybe I can direct the dealer in the right direction.

 

Clean out the TB?

One of the sensors on the system is acting up?

Had this problem on one of my bikes which came from the factory with the setting on the TPS (throttle position sensor) so the emissions could pass. Obviously this not the issue in your case but in my case the TPS would read the butterfly valve's setting at an inittial setting which was to lean -- so for the first 2000 RPMs the system would hunt for a mixture that coresponded to the rest of the information that corresponded with all the other inputs. That is why I say the TB -- specifically the butterfly valve. If it's dirty and sticking then the TPS will not be able to send the correct info in a consistent manner.

Keep in mind that I am not familiar with the Tacomas system so I could be off base. Hopefully some one with more knowledge will chime in.

 

What is an IAC?

 

u sure ur not just feeling ur a/c compressor -engine idle up...? when driving w a/c on

 

I first did start noticing it when I had the a/c on, but I haven't been running the a/c on purpose to see if I still felt the surge. Sure enough its still there.

 

Thanks for the suggestions. I am gonna look at all these options, hopefully it will correct this problem.

 

Clean out your IAC if that doesn't fix it then look for a vacuum leak.