1998 Tacoma sputtering/lagging

I recently purchased a 1998 2wd single cab manual 2.4 L engine. I love it so far however I am noticing something a bit strange or at least strange to me. When accelerating in 2nd gear it likes to sputter a bit and I notice a similar feeling when driving at constant speed and rpm in 3rd and 4th gear. It’s like the truck will be driving fine then there will be a sudden millisecond or so of lag strictly that I feel in my seat. Almost like if someone were to slightly touch the break very suddenly and lightly. I do not have a Tach so I haven’t watched the rpm’s yet. Additionally it does not seem consistent at all. I have read similar “lurching” tales on the forums however it seem like everyone else has some worse symptoms. Does anyone have any idea of what might cause it? I just bought the truck so haven’t had much time to do anything with it yet however I plan on diving in this weekend. Thanks!

 

Additionally I would like to say it has 250k and everything else feels great. It idles nice I did notice once warm it likes to drop in rpm and give a slight shake but that is it

 

I'd start at spark plugs. And check to see if it's throwing any codes.

 

Alright so I still have not gotten to the plugs yet, however it did just throw 2 codes- p0300 and p0301. I will do plugs now. Also it has been doing this thing when it warms up and tries to idle it idles extremely low to the point it sounds like it’s going to die. Also the lagging issue only seems to be when it is warm. Any other diagnosis help would be amazing! Thanks

 

When you say low idle, how low? Under 600? If it is only while warm and at idle, I would check for vacuum leaks and operation of the IAC.

I also have a significant vibration at idle when warm, around 650rpm and have replaced injectors, plugs/wires, cleaned the throttle body, replaced vac hoses, fuel trims are under +10. Thinking it is related to IAC.

 

I have gone through a hole can of brake clean trying to find a leak and can’t found two dry rotted vac hoses and replaced those still same deal. I am getting a a new pcv valve (relatively cheap so why not) after that I will most likely check out or get a new idle control valve.

 

Before replacing the IAC I would check out the throttle body, it may be really dirty.

But also reading through the post again, are you sure fuel pump/pressure is good?

 

I have checked and don’t know how to. Do you have any recommendations on how?

 

It sounds like you did spark plugs? What about the speaking words and the coil packs? Or is it a distributor? You need the things for combustion, oxygen, fuel, and spark. Air is unlikely. Fuel could be an issue, such as a weak pump or injectors failing. But the easiest one to do is your ignition system. I'm my experience, a misfire is usually due to one link in the ignition system.

 

Speaking words?

 

Haha autocorrect got me! Spark plug wires

 

I am unsure if there is an easy way to check fuel pressure. One time I just disconnected the line pointed it to a bucket and cranked to see how much fuel shot out. Seemed like enough to me

 

Hey guys, I currently have taken the entire throttle body off and am cleaning it all. waiting on gaskets to re-install it. One thing to note is that right before i bought it the previous owner had the O2 sensors replaced. Do you think they could be faulty or a bad brand and would that cause the issues i am experiencing? THanks

 

hey guys, I finished installing the new IAC and cleaned the entire throttle body. Started it back up and drove it for 10 minutes or so and its still doing the exact same thing. So far I have -
Cleaned MAF
Checked for Vacuum leaks (Spray of carb cleaner everywhere)
Used seafoam
replaced IAC
Replaced Spark Plugs (with correct ones)
O2 sensors were replaced right before i purchased it
Replaced PVC Valve
Replaced 2 Vacuum Hoses that were a bit shotty
New air filter
additionally the Denso spark plug wires do not look like the original ones I assume they were replaced at some point. (they have markings on them for which cylinder they go to, i think a mechanic probably marked them when they replaced them)

 

Spark plug wires and coil packs are pretty cheap. Replace them and since you already did the spark plugs, you can completely rule out it is related to the ignition system.

 

Have you checked valve clearance?

 

I see you pulled a couple of codes from the ECU. I never saw where u did anything with the codes. What do they mean? That should direct you to the problem.

 

P0301 is misfire on cyl #1. Swap your coil packs around, clear the codes and see if the problem moves.

If this doesn't locate the problem, swap fuel injectors and clear the codes.