Bruin425

About 3 weeks ago I started my truck (I live in the PNW, Seattle, WA) and immediately while driving down the street felt an extreme loss of power/hesitation. It felt like the truck shut off and then started again in a lack of a better way to explain the situation. I thought moisture was in the dizzy cap so I hammered on the throttle but it would just chug chug along (low rpms and hardly any throttle response). Eventually after city driving for about 10 minutes the loss of power/hesitation went away. It has never done this before, ever! So it was super strange to me. I continued to drive the truck each day but the severity was very low. What I mean by that is how bad it was the first time has not happened again. Currently, I get about a one second loss of power/hesitation 90% of the time in 4th gear at 40mpg and in 5th gear at 60mph. Sometimes is happens the entire time I'm in those gears and sometimes I do not feel it at all while driving. When I do feel it, it feels like you took your foot off the gas pedal, then put it back on, and then you feel the inertia. I hope you can understand what I mean. It seems to me like something is shorting out somewhere? It starts up first try every time. But today it went back to extreme severity (see attached video) that's what I'm talking about. The one second hesitation and loss of power you see in the video.

I checked all fuses with test light and all work.
I checked the engine bay, nothing seems out of the ordinary.

I replaced the spark plugs, wires, cap, rotor, and fuel filter about a year ago.

I have not taken the bed off to check the fuel tank for wire condition or corrosion or ran a fuel pressure test.
I have not done the diagnostic test for the fuel pump.

I did purchase a fuel filter. Someone brought up the point I could have purchased bad gas that had water in it or rust from my tank messed up the fuel filter. This Wednesday I will be doing everything I said I have not done.

Has anybody experienced this or can give me any advice? Is there something I'm missing?

87-4runner

Throttle Positioning Sensor
mine acted like it went into limp mode.
when in park will it Rev to a certain RPM then drop back or bounce back and forth in RPMs?
IF that's how it acts then UNPLUG the TPS and see if it revs normally...IF it does your TPS is shot.

Bruin425

Its only idled bad like that two times. Check out the video I posted of the weird idle. Next time it does that I’ll try the tps

Bruin425

i unplugged the tps and it idled the same. But then I ran the diagnostic test and it showed a 41. The throttle position sensor. So I don’t know if it’s showing that code because I unplugged it and it hasn’t reset yet? I should’ve ran a diagnostic test first.

87-4runner

Unplugging the TPS won't change the idle...
it will however let you REV the motor to 4k rpm. IF the TPS fails you won't be able to REV it without it kicking itself out and dropping the rpms back down.
mine jumped between 800 to 2500 .

Bruin425

Oh! Gotcha. So this morning when I was testing stuff out it had that weird idle like in the video. Now at night time it didn’t have that weird idle. However, with tps plugged in I would rev it and feel like a rumble coming up under my seat. But I took it for a drive and it drove without the issue happening. Super weird man. And it’s been raining all day.

Bruin425

I ran the truck with and without the tps and it seemed to the same idle range. Although I checked the diagnostic box again and the light still flashes a 41 code. Should I just replace it and see what happens?

87-4runner

This is just ME.. OK?
IF the TPS is the 30+ year old one I'd get a new one and be done with that issue.
the TPS can create issues and that would eliminate some of them...
Same logic for fuel filter, fluids, plugs, dizzy cap, wires, fuel pressure regulator...
Some items that your gonna deal with someday if they haven't already been addressed. Not terribly expensive items.
it may not "fix" your problem but, again it eliminates a few of the possible parts that could be or will be... just me.
ideally you'd make the changes one at a time and SEE what difference it makes, so for future reference if your experiencing similar conditions you might recognize the symptoms and recall what the fix was... sometimes that works and sometimes it doesn't argh...
enjoy your 88 and good luck with it., these 1st gens are great little rigs.
sorry... one more thing
Seems like the two most common BIG issues are the head gasket and timing chain guides. Other than those two Achilles heels, the 22r, re, Rte are bomb proof.