Injector issue? 3.4

So I've tried all the vehicle specific and generic forums looking for some help with my issue but figured I'd give it one last shot here before I take it to a mechanic.

2000 Toyota Tacoma 3.4 V6 5 spd 110k miles

I had a bit of a misfire which was causing some brutal jerking under heavy load. Realized that it had to be plugs based on it running fine when I was gentle on the throttle. New plugs did indeed solve this problem.

Now if I up shift into a higher gear or go up a hill and give heavy throttle while in low revs I get a pretty significant buzz/vibration. Thought it might be a resonance thing from the exhaust. I changed the original muffler as it had some things shaking around in it inside. This also didn't solve the problem.

Now I'm kind of lost. I thought it might be a fuel delivery thing but it didn't make sense as at high RPM it doesn't happen. I ran seafoam through the intake and gas, cleaned up the throttle bottle, checked for any loose bolts, replaced a couple bearings a month later during t belt and water pump change, and I've made sure everything is all greased.

Best ideas I have now is a messed up injector, or a driveline issue (carrier bearing or u joint - which neither make a ton of sense due to occuring in heavy load at low RPM only).

Any help or ideas would be greatly appreciated.

 

if your hearing a "buzz" from the engine then check the exhaust heat shield, they can crack at the bolts and under load they will "buzz", also check the exhaust heat shields, especially the cat, because they too can "buzz" while vibrating under load.

 

Hook up a scan tool (or Bluetooth dongle with the Torque smartphone app) and see if you are getting misfires or any other codes.

If your scan tool has real-time data, look at the MAF airflow and make sure it's seeing reasonable values when the problem occurs.

Do you see/hear any vacuum leaks?

 

Under Heavy load your driveshaft would be on less of a angle, so the shake most likely isn't related to that. I think the heat shield should be checked as well, Check your coils and wires as well?

 

Keaker - will check and report
Kenlyns - there's no CEL, I do have torque and a Bluetooth dongle so I'll check the maf value. That sensor was cleaned at some point in the middle of this by me. Already checked for vacuum leaks with a good inspection and a propane torch.
2stroketrush - new wires went in at the same time as plugs - will check coils

All bases will be checked this weekend. Just gathering info for a plan of attack.

Thanks Gents

 

id say first you want to check the motor and tranny mounts. if they're bad, they're not properly absorbing the engine vibrations. a bad tranny mount will also pull the CB down and make it seem good and tight.

second. grease your ujoints to eliminate the possibility of a bad carrier bearing. if the noise dies down. your CB may be shot. if it didn't change anything. the issue is elsewhere.

lastly, on an extremely rare case, i highly doubt it but im going to mention it anyways, the clutch pad springs are old (or one is missing) and not absorbing the "combustion spikes" from the cylinders.