Auto trans.

Ngk wires and plugs, 3-4 years old.

Cap and rotor, same age, as is the fuel filter.

Timing dead on last time I checked (within the past 2-3 months)

No CEL

New denso o2 sensor, factory replacement.

Just swapped in a different TPS thinking that was the cause. Issue is still present.

Around practically 90 percent throttle, you can hear and feel the motor bog down..

Lift a little and it surges. More throttle past 90 percent and it usually downshifts(depending on speed) and pulls hard.

Idles beautifully and putts around town great, this is only evident when trying to accelerate hard.

When free revving the motor in park or neutral of you kick the pedal WOT out of nowhere it'll miss real quick, and then rev. Kinda like a hiccup.

Any ideas on where to troubleshoot without starting to replace components? It's had this issue for awhile now. Thanks for any suggestions in advance.

Note: I noticed when replacing the tps that there is adjustment in its position as you lock down the two screws. I tried to match it's position based on the marks on the old (original) one.

Bahummp.

Had an issue with my 87 spfi bogging about 6 months ago. No codes at all. Went from slight to cutting out under any load but would rev freely in neutral. Got so bad that I had to rev the engine while slipping the clutch to move. Limped home that way.

The ignition module had failed in the distributor. Replaced the crank angle distributor with a used one.

Later on this killed my cat converter so that had to be replaced too before I could pass smog.

 

Here's the TPS switch adj procedure from the Haynes manual.