98 4runner 3.4 auto…been dealing with some ongoing low acceleration issues. This thing is an absolute dog until I hit about 3/4 throttle then it takes off like normal. New oem TPS, new denso MAF, new denso upstream/downstream o2 sensors, fresh fuel filter, new ngk plugs and wires, no CELs besides the ABS light. Looking at my LTFTs it idles at +11, if you roll into the throttle real light it will drop down to +2.3 and stay there at cruising speeds. If you hit it at WOT it drops to -13, thinking possibly the FPR is junk. Pulled the vacuum line off and had no fuel coming out but it also didn’t idle any different with the vacuum line off. Swear I read somewhere that it should idle up with the vacuum line removed. Any suggestions? Checking fuel pressure tomorrow to see if I can confirm my suspicion.

 

+11 LTFT at idle means its adding fuel, WOT would ignore sensor feed back mostly. Perhaps a ECT sensor, check the actual engine temps it uses for fuel trims not the gauge temps, there are 2 separate sensors for these. this is my first thought since you swapped MAF, TPS, and Front O2, either that or a bad sensor or bad intake leak, but that doesn't jive.

 

I swapped the ect sensor awhile ago with no luck but it was just a crappy autozone brand. When I hook up my scanner the coolant temp looks normal compared to the gauge on the dash. I’ve smoke tested it quite a few times and haven’t seen anything. If you try to accelerate at about 1/2 throttle you can feel it slightly surging like it wants to take off but something’s holding it back, then once it hits 3/4 it takes off.

 

Then I would suspect Clogged/old injectors(but that should flag a misfire) or weak fuel pump perhaps, not easy to plumb in a fuel pressure gauge at the rail banjo bolt, but maybe at the supply line to rubber line leading to the fuel rails. Kind spit balling ideas now, 98 would have the old style injectors which don’t fail as often but a friend in town just had to do a 2nd injector on a 96’, they aren’t cheap from Toyota, plus you need to do the seals aswell.

 

I was thinking injectors as well. Was thinking about pulling them and sending them off to Motorwest performance to get re-done. Just so odd that it runs lean at idle and then goes pretty rich on acceleration. The parts roulette game is not fun, once I test the fuel pressure I hope I get a little more of an idea to what the issue is.