It seems like the engine is misfiring?

It is possible you need a tune up but it could be a fuel injector as well we should run the codes to see what's going on first.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

and

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

and

https://www.2carpros.com/articles/how-to-tune-up-a-car-engine

Please run down these guides and report back.

Diagnostic fault codes never say to replace parts or that they're bad. Without knowing the exact code number I can't help with a plan of attack, but if you had a misfire code, you need fuel, spark, and compression. One of those things has to be missing. A quick trick to identifying the likely suspect is to switch the injectors between the misfiring cylinder and one other one, and the ignition coils between the misfiring cylinder and a different one. For example, switch the injector from cylinder two, and the coil from cylinder three. Erase the code, drive it, and see which code sets next. If cylinder two is misfiring now, suspect the injector. If it's still cylinder one, look at compression, worn camshaft lobes, and things like that.

Try swapping two injectors.

Gotta run now because my 'puter battery is dying. I'll check back later to see if you solved the problem.

If still a miss fire check coil if coil over plug, or ignition lead and cap, check that the injector has pulse and it is firing, check for a vacuum leak around the cylinder, start here.

Mark (mhpautos)

What is the misfire code? P0300?

Run the car @ idle. Start pulling ignition wires one at a time to see which cylinder is not firing. Start hear

Because the engine wont change when you get the cylinder that is not working.

This sounds like an ignition problem. The jumping tach is a good clue. The possibilities are EDIS module, crank position sensor, or cam position sensor. One of these is giving erratic signals that cause the car to jerk and the tach to jump. Before replacing parts, though I would check all of the related connectors for corrosion or loose contacts. Also, check the harness for any chafing that may cause an intermittent shorting to ground.

Sounds as if you have a vacuum leak at the brake booster, to check this, pull the vacuum line from the booster or the manifold which ever you fine easier and block the port, run the engine and press the brake, if the problem is solved, you will have a faulty booster.

#3 is the last plug in back near the driver, you must remove the upper intake manifold to access the coil on plugs, When you do get in there you might find a torn boot.