Vehicle Specs:
2004 5VZ-FE, Tacoma, 5-sp, 4WD, 42K miles

Problem: A slight, intermittent hesitation when driving under the following conditions:

Engine temp: Operating temperature
Outside Temp: Varied
Throttle: Light
Gear: 1st, 2nd, or 3rd
Speed: From 5-35 miles per hour
RPM: 1,800 - 2,300

After searching, (and after cleaning the MAF) I began to suspect the TPS, but reasoned that before I look into testing the TPS (or other sensors) I should start by cleaning the throttle body.

Using Deep Creep spray; some clean, lint-free, rags; a toothbrush; and several long Q-tips typically used to clean firearms, I cleaned the throttle body throat, pivots and butterfly valve. There was a thin (~2mm) ring of carbon around the throat at the butterfly.

Outcome: No more hesitation. I have attempted to induce the hesitation by driving under all the conditions outlined above, but the throttle response has been smooth and linear.

 

Nice write up, thanks for posting.

 

Yep, one easy thing to do during a time of tuneup. Just did my buddies 96 T100 the other day actually... he'd had his truck for 119,000 miles and never cleaned the throttle body. Thing was caked... runs 10x better.

 

I had a similar problem. Main symptom was...when idling... just tromp the gas and instead of the RPMs going up, they would drop by 200 or so and then sluggishly accelerate. If the engine was cold, it would even backfire when the RPM dropped. There were problems of this nature at other speeds but the description above summarizes the worst of it.
Even though the MAF checked out fine for resistance, I changed it and all was well. Then for curiosity, I took out an artists paint brush (tiny) and cleaned the grunge off the old MAF paying attention to the little wires and the thermistor? thingy. The old unit now works as well as the new one. Too bad I did not start there.

 

I had a similar problem with my '88 P/U. The butterfly was getting stuck on the dirt ring. It would hesitate & I could actually feel the throttle stick sometimes.

 

Good work! Didn't know that 2mm of carbon could do that.