2000 AC tundra v8 running rough when I punch it.

Okay so it's been a while since I been on the forms. Here is the quick update.
I got my wife's grandpa truck. It sat at the dealership for a year because it needed a few things.
I have since got it running and have replaced the following.
Starter
Battery terminals
Fuel injector rings (when replacing the starter)
Intake gaskets
Throttle gasket
Clean out throttle and ran Seafoam through it
Replaced all spark plugs with copper ones and gapped to .032
Replaced all coil packs
Just replaced fuel filter today 3/25/20
Both front 02 sensors

So as I have done these things it runs a little better, but it still bogs down when it downshifts. Almost as if it has been miss firing but it hasn't thrown any codes. Tell me if I'm wrong, but I feel as if one of the injector might be clogged or something. Or is there something I'm missing as far as doing. I didn't pay anything for the truck so the investments I have made haven't broken the bank yet so I'm just trying to get it running right so that I don't have an issue with it. I daily drive it, but I have to be gentle with it. It's really strange what is going on. I can't seem to find the issue.

Could it be the throttle is still dirty? Or MAF sensor is dirty? Air filter is new. One thing I have noticed is that when I come to a stop it sometimes has a delayed punch as if the transmission didn't shift out of gear. I'm not sure if that's a common issue it if that means it might be my transmission doing something funny. It really doesn't sound like it's anything to do with the transmission and more with something not firing right on the right side of the engine.

Anyway this is super long, but thanks either way. I'm taking a trip from Portland to Baker City today with it so we'll see how that goes. I have no doubt it will work just fine it will just go slow on hills and might have to take my time.

 

Fuel pump resistor or relay?

 

Where is it located and would that happen if it's heating up?

 

I'd clean the MAF Sensor. It can cause the symptoms you describe, it will take about 5 minutes to do, and will only cost you the price of one can of MAF Sensor Cleaner.
Even if it doesn't correct the problem, you'll have ruled it out, and it's a mainenance item that should be done periodically.

 

Clean the MAF!

 

I will be doing that when I get home this weekend.

 

I run a little rough after getting punched, as well.

 

Sounds to me like you have a vacuum leak . One of my old fords was doing exactly what you’re describing and right after a tune up , turned out to be a vacuum line that got knocked off .... put it back on and it ran like new .

 

I'll check that in the morning. I did get a code while driving back home. It's p0304 which says cylinder 4. So the strange part is that I have replaced all the coil packs and spark plugs. I think it might be an injector. I'll try to switch injector as well and see if it keeps doing that. I'll also clean the MAF sensor and see if that helps.

 

I had a car in the past that would fall on its ass when I floored it but would run fine otherwise. The catalytic converter was replaced and all was good. Just another idea. How many miles on the truck?

 

You know that's something I thought of because when I got the truck the 02 sensors where bad. The truck only has 146k on it. So it could be ready for new ones. The only thing is that I got that misfire code so I'm going to try and rebuild the injectors and see what happens. I found a kit online for $27. While I wait for that to arrive I'll trying cleaning the while right side injectors and see what happens. If and when I rebuild the injectors it doesn't solve it I'll have to see replacing those would help.

 

Did you clean the MAF Sensor yet?

If not, note there are two "elements" to clean. The more important one is the one that's sort of hidden.

This video shows it pretty well: (Although I'm not sure why he doesn't use the red nozzle -- particularly to spray the harder-to-reach element?)

https://www.youtube.com/watch?v=orJ6rXP4xQg

 

I cleaned MAF Sensor and Intake as well. I also tested the compression on all cylinders and they are all around 180 to 175. I brought it to a shop in town and they took a look at it and said they think it might be the pucks in the valve train. Has anyone had any issues with this in the pass?

 

Valves out of adjustment would be quite rare -- particularly at only 146K miles.

When you replaced the ignition coils, did you use aftermarket or OEM parts? If aftermarket, try swapping one of the old ones back in to cylinder #4.

 

I got aftermarket ones and I have swapped OEM denso ones on that cylinder and still get that lack of power and miss fire.

 

If you didn't use NGK spark plugs when you replaced them I would install NGKs. I would also change them to iridium from copper. I have never got a misfire code from using copper but have noticed both my 4.7s run better on iridium plugs. And brand also can make a difference.

 

They were NGKs

 

is it only when down shifting? what happens if you hold it in 2nd gear at say 3500RPMs and punch it?

 

Any update OP?