possible ignition problem

My 2004 Taco is not running at 100%. This is a 2.4 engine. The power is just not there. I can drive it. But it is sluggish. If i press on the gas, going down the road, there is a sweet spot. If i press down any further, it actually retards acceleration. This engine sat up for well over a year. I have put over 1,000 miles on it since. it runs much better since I ran a tank of gas with injector cleaner in it. The funny thing is, within the last 4-5 years ago, it was doing the same thing. I replaced all sparkplugs (High quality Ididium) and Delphi coil packs. It ran like new! It hasn't been that many miles ago. The spark plug tips look good. Very clean. Those are good coil pacs. Hard to believe they would fail. I have another 2.4 engine i could barrow from to test. No codes showing related to ignition. What else can i check? Going out buying parts, just hoping it fixes it, is like gamboling. Throw is to the wall, and see what sticks.
Any thoughts or ideas appreciated.

 

So you did all the obvious???......clean the maf sensor..
look for vacuum leaks.....including the brake booster, and pvc system...

any possible voltage brown out sources...got strong battery....good grounds all over the engine..

I would recommend getting/borrow a decent scanner that you can drive around and look at live data.....see if any of the stats(sensors) seem out of range or wonky...

exhaust leaks from the header to that first O2 sensor would/could cause a tailspin for the ecm trying to cope.

That blue driver dongle is only $100 and is fairly popular here...
that will let you observe air volume, ect temp, fuel trims, O2 status, whether the egr valve is opening/closing at the right times....ect..


the 03/04 owners might be your best bet for advice simply because they have unique experiences to those..

Yours has that electronic throttle body ...and that troublesome pedal position sensor, not talking the throttle position sensor..but it can still can be that too....
there are old threads on to deal with that.....and someone came up with a way to overhaul that pedal sensor too....or at least make it last a little longer...

and then the vapor canister is wayyyy in the back....so you (03/04)'s have more lines and related systems that create more points of failure....even a wonky gas cap....

So many things....so little money....

alot of times its just something really stupid simple......always assume that first....
instead of something like new ecm, or new this or new that....
could be as simple as one of the sensors have come unplugged....or a bad wire or connection to it...

good luck....and we dont get alot 03/04's problems here....so others will pull up this thread in the future.....FOR SURE.......dont leave em hangin.....


any others have ideals.....jump in.....wont hurt my feelings.....dont think I have any...

 

Sorry for the late reply. I don't think there are vacuum leaks. I am not sure the correct identity of the MAF. Brakes are good, although I have a indication. Likely a sensor not seated properly. Battery is good. It does squeak when I wind out the gears. Like a belt, but the tension seems right. I have a scanner. I can look for live data, but to be honest, I don't know what it is telling me. I do know I have a CAT sensor alert. The vapor canister makes my SES light stay on permanently, thus rendering the system useless. It was that way when I bought the truck. I was told that part was unavailable.
I spent time swapping parts from the donor truck, but nothing seems to help. I was hoping that driving it would settle it down. It has some. I may need to carry it to someone. That, or just put up with its sluggish acceleration. This is why I hate electronics. I understand the goal. But in an effort to make things more reliable and efficient, toyota has succeeded in the opposites effect.
Thanks for your help

 

When you plug in your scanner there are a few things to look at first. Start with fuel trims, your device might show something like STFT bank 0 or something similar. You want to know what your short term fuel trims are. An easy explanation is 0.0 is a well running engine base line. A +10.0 means that the computer is adding 10.0% more fuel a negative number means the computer is taking away fuel. A +- 0 to 5% is quasi normal and is nothing to be concerned about. If it is in this range, your problem is something else.

Is the CEL (check engine light) on, if so, get the freeze frame data and post it here. This is what happened the instant that the CEL illuminated.

 

I was wrong. It IS showing codes PO325 Knock sensor, and P0135 Sensor heater circuit bank1, sensor 1

Live data
DTCFRZF PO135
Fuel sys A OL-fault
Fuel sys B -
Load-PTC% 23.5
ECT (C) 83
Shift% 0.0
Long FT% 0.0
RPM 678
VSS (Km/h) 0
IAT 26

What is this telling me? I can do live data and post it here as well. I know RPMs is likely low. The engine would die at idle. I got it where it would stay running, and left it there.