1999 Toyota Tacoma + problems in the fall season - only during warm weather

I am throughly convinced my 1999 Toyota Tacoma is a cold weather vehicle. Its an automatic standard cab with 134000 miles v4 2.4l engine.

I had a problem last year where the problems only occurred when the temperature outside would go from cold to warm (60+ Fahrenheit). This year my truck has a new issue that still only occurs when its roughly 60+ degrees outside, otherwise it runs just perfect.

Anyways, now it will start up just fine, but after I start to drive it for about 5-10minutes it will seem to hesitate in sort of a jerking motion. Slowing down or speeding up does not improve the problem. Slowing down after driving for 10min acutally causes it at a faster frequency until I have fully stopped. The only solution so far is to turn it off for 20-30minutes and drive again.

I have asked local experts about the problem and it seems to be a very strange and unusual problem. I have checked all of the fluids (oil, power steering, transmission, etc), I am on my second replacement set of spark plugs that I have replaced. I replaced the brake pads earlier in the summer.

Any advice or any help on troubleshooting would be greatly appreciated.

I have been told that this could be a mass air flow sensor problem. Although the check engine light has not come on. Is there a way to trouble shoot the sensors without replacing each one or is it more economical to simply replace them one by one?

Are you convinced this is an engine problem rather than a transmission problem? It sounds to me the trouble my be something within the drivetrain.

I am not certain that it is. Although I am a technician, I am a computer technician, so the parts & inter-workings of automobiles are somewhat foreign to me.

From what I have read and gathered from asking is that it is more of an engine related problem since it does not happen on a continuous basis, but a predictable basis.

For what its worth here are some of the websites that I have looked at:

I will check into the drivetrain as a possibility is there anyway to troubleshoot to see if that is indeed the problem?

You could try putting the shifter into neutral while the trouble is occurring and see what happens.

The IAT (Intake Air Temperature) Sensor or the ECT (Engine Coolant Temperature) sensor could be sending bad signals to the engine computer. They are inexpensive enough that swapping them out is cheaper than paying for a diagnostic.

I put it into neutral a few times while the problem was occurring and it did not seem to make any difference.