My trusty '87 4Runner (180k miles) 22RE has had flat (stuttering) performance accelerating through 2,000RPM, but a couple changes have brought it back to its old self.

Step1: Replaced 15yo plug wires, cap, rotor, plugs with new factory parts. This helped a bit, but not a lot.

Step2: Cleaned throttle body. Mechanic at the dealer advised this would fix the rough idle. This is the fix that seemed to make the difference. Idle is notably smoother, and there's no flatness on acceleration when passing through 2,000RPM any more.

Throttle body (TB) cleaning:

This is pretty easy, actually, though I'm sure it can be made much more complicated. My goal is to share the level of cleaning I performed and how it helped me. More thorough options are certain available.

Step #1: Remove the tube connecting the throttle body to the filter box. A philips screwdriver is all that's required.

Step #2: Remove the three vacuum small hoses from the TB top. Note where the connect (not sure if it really matters) so they can be returned to their original connection points. No tools required for this step.

Step #3: Remove the large vacuum tube that goes to the right near the TB inlet. Small pliers required.

Step #4: Remove the throttle cable by rotating the throttle plate clockwise to put slack in the cable, and then rotate the cylinder on the end of the cable free. No tools req'd.

Step #5: Remove the three bolts and one nut that secure the TB in place.

Now gently pop the TB free from the intake manifold and pivot the top toward you. There will still be two coolant lines attached, but I didn't find it necessary to remove those. (nor easy to do so).

For cleaning, I used simple paper towels to wipe out the bulk of the 180k miles and 25 years of accumulated gunk. Next, I used a toothbrush and Goof Off to scrub and dissolve the remaining gunk on the walls of the TB and the butterfly plate. Additionally, I cleaned what could be easily reached in the intake manifold, but for a really proper cleaning that would need to be removed.

Assembly is as expected, simply reversing the above steps from 5 back to 1.

All-in-all, an easy process that netted very worthwhile returns in much smoother idling and no more flat acceleration through 2,000RPM

 

Yep, it matters. The ports are sequenced to throttle valve position so as to operate associated components under specific conditions. Have a close look at the TB and you'll see the ports are labeled with designated letters.

Otherwise, nice write up!