Desperate to fix vibration and jittery driving issue

I recently took my 2008 Tacoma Prerunner in for a 90,000 mile service along with a few other maintenance items. I had the spark plugs replaced, serpentine belt, rear diff oil, air filter, and Icon coilovers revalved to be a tad softer. I also picked up a new set of BFG A/T tires.

Ever since taking my truck in I've been having a constant vibration through the steering wheel whether in neutral or drive. Additionally, the truck seems to drives differently and feels less powerful and somehow louder. When driving at freeway speeds I also feel like the truck is extremely jittery and not smooth riding at all with significant steering wheel vibration. After having so much work done at once I'm not sure what it could be but it's driving me nuts!

I tried having the tires rebalanced and that didn't correct the issue. I also reset the ECU thinking the spark plug change may have affected the drive quality with no effect. I'm not seeing a check engine code or anything appearing on the instrument panel. The truck also tracks straight so I'm doubting that it could be the alignment.

The shop I went to used the appropriate spark plugs from what I can tell but somehow I feel like that may be the issue. I took it back and they swear they couldn't find an issue. I've had my Tacoma for 90,000 miles now and KNOW it drives differently and am pretty unhappy. Any thoughts on what could be causing this?

 

When you say it vibrates in neutral or in drive, I will assume that you mean only while the truck is at speed, not idling at a stop?

If it idles smooth with no check engine light, I think you can rule out the engine and focus on the new tires. The last set of tires I bought, the fools at the tire shop claimed Toyota wheels are really hard to balance, and so are AT tires. I know that there are hub centric wheels and lug centric wheels, Toyota is usually lug centric, and there is an adapter for the tire balance machine. It's possible they are not mounting the wheels onto the balancer properly. It's also possible you have an out of round tire.

In my case, I went back to highway tread Michelins, I don't do much off roading, so I chose to just get by in those situations, rather than keep trying to make incompetent people do their job correctly. I figure the Michelins don't take hardly any weight to balance, so even if they do a lousy job, it probably would drive just fine still. I was right. If you've got Icons on your truck, that probably isn't an option for you. I would get a second opinion on the tire situation.

I once ran a vibrating vehicle up to 60 MPH while it was on an in-ground shop hoist. It did not vibrate while in the air. Turned out to be a bent wheel. Tire shop kept saying the balance was okay, etc, etc.

Alignment isn't going to cause a vibration.