Ok, most of you know that im having a hesitation problem. I just replaced my o2 sensor, thinking that it could be the final peice to my puzzle. Now, the engine sounds fine. It idles fine, revs fine, and sounds fine under load. The hesitation has gotten worse with the installation of the o2 sensor. I can hear a pop, or something to that effect when the car hesitates. The only things i have not replaced are the map sensor, tps, idle air control sensor, and cleared the cat. I am truely thinking that my clutch could be slipping. Most of the hesitation occurs in gears three through five. The weird thing is, when i turn on the ac button without the fuse in the box, the car runs a little better, but after changing this o2 sensor, its made it worse. Can ANYONE please help me. Just ramble off a check list of any sort, make stupid suggestions..(not plugs and wires please) This is a serious question and ive tried all of the minor fixes. TIA!!

Well not to bring plugs up, but the gap is very critical and has always been the cause to my hesitation probs. I've always had to gap them a little lower then the spec. Other then that, Your fuel pump may be getting weak, Yes it does happen and would cause the problem. The only way to know 4 sure would be to change it. Crawl under the car and trace the fuel lines along the bottom of the car and make sure none of them are pinched or kinked, trace them all the way to the motor.

ran any fuel injector cleaner through it try a bottle for gas tank fuel injector cleaner and use some thorrtle body cleaner, have th car checked for codes, a couple to add to the list =)

If it is your clutch, then when you push in the gas in 3rd-5th, then the rpm's would climb quickly but the car would not accelerate. You would also small a burning smell in the engine bay after it happened. Have you done a compression test?? It's possible that the map sensor isn't working properly, or perhaps the cam angle sensor is slightly off or the cams could be out of alignment...

Cam Sensor
Crank Sensor
MAP
Air INtake Temp Sensor
Coolant Temp Sensor
Dirty Intake Manifold
Clogged Cat or exhaust leak
Vacuum Leak?

Well you wanted alist, here's some thing you could check...

Una salus victus.
He will triumph, who knows when to fight, and when not to fight. - Sun Tzu

Michael J. Kulaga
e-mail: Michael_97RS@2gntDSM.zzn.com aol IM: MJKulga
http://highlander.dsmpower.com/

All motor in the making.

Injen CAI, P&P Intake Manifold, Crower Stage 2 Cams, Hooker Header, GS-T Muffler, AFX UDP, S-AFC, 8.5mm Magnecor Wires, Crane Fireball HI-6DI2, FU/RU/RL STBs, TSW Blade 17x7.5, Bridgestone Potenza RE730, Front KVR Cross-Drilled Rotors & Carbon Fiber Pads

To Be Installed: P&P Milled Head, Rear Disc Brakes, Rear KVR Cross Drilled Rotors & Carbon Fiber Kevlar Pads, SS Brake Lines, AFX 55mm TB (re-installed once exhaust is done, intake was outflowing exhaust)

yeah i know the hesitation thing sucks..i had it for a while and i changed plugs wires and injectors...no hesitation. and the symptoms sounded the same..first it started to happen low rpms, then gradually more...it may have been plug wires...mayb have been injectors goofing up. reguardless, its not the collent temp sensor or air intake sensor, 02 sensor or slipping clutch...i know that for sure...i replaced them and they didn't make a damn differance...hope that helped a bit..good luck.

it sounds more along the lines of a fuel problem...in 3rd gear and up the engine is under more of a load and if the fuel is not sufficient to keep up with the increasesd load, hesitation will happen....

Thanks for all the replies guys. I didnt think anyone was going to help me out. Most of the time when the hesitation occurs i smell gas coming from the motor, no where else. Im going to try and get the cat cleared, and i think i filled my tranny fluid in the wrong spot(dont ask). Now as for the air intake temp sensor, where is that? When i turn the ac on, the fan blows cooler air into the intake and the car doesnt hesitate as badly. Anyone else have any suggestions? Thanks again for the replies

If you are smelling gas, then this could be a problem of you running seriously rich! Of course this is after i turbo'd but i wasn't getting enough air into my cyl so my plugs were loading up big time with carbon. So try that out too, if you find that you are getting sufficient fuel, you may be getting too much, try widening the gap out a bit on your plug, what you got to loose? Maybe change to a warmer plug so you can sling a hotter spark, and then burn more fuel. If the hisitation sounds kinda like something is loading up under there and you feel the exhaust in the back and it feels more thick then normal (if you are familiar with what stock exhaust flow should feel like) then i would bet you are getting too much fuel for some reason.
Just throwing out something else for your to look at. Good luck.

Danny.