Trying to locate problem with misfiring/rough idle and slow accleration

will more than lightly be plugs or leads sounds like misfire i.e.one or more cylinders not firing

wow a 99 an oldie but a goodie , one that old id be looking at all the vac lines , for pin holes,worn spots and cracks , a vac leak will make engne run rough at idle and as you acclerate the vac goes away so hole in hose does not matter

Check your vacuum lines and be sure your throttle body is tightened down. Carb cleaner spray can be used to find the leak. Spray it around the lines and gaskets (while the engine is running). If the idle speeds up, you found the area of the vacuum leak and the solution to your problem, possibly.

Code P0505 is Idle Air ControlSystem. P0300 is Random Misfire. P1151 is Lack of HO2S21 Switches- Sensor Indicating Lean. Possible cause is Idle Air Control solenoid.

youll need to check the vacuum lines on the 4.6 engine in the back where the pcv valve is look when running , the engine is the pcv hose collapse? is there any vacuum hose leaking at idle, this will cause a lean misfire upon accleration. okay no vacuum leak let the vehicle cool off.when this vehicle is cool you are going to run a test you can do this you did a tune up. start the engine test the EGR the top of the valve. does it get hot? feel for it . does it get warm. I mean like it get hotish. this valve can be stuck open. okay , do this on the EGR is a hose pull it off does the idle from rough go away? if it does this is the problem.You did everything right you need to solve for vacuum leak use your ears

Possible Idle air control, simple to change on the throttle body

Fuse box is behind the soft panel under your steering wheel. Is your check engine light flashing or on? Would be a misfire causing the rough idle if it is flashing. A possible bad coil. If its just a shake with no check engine light then it could just be a motor mount.

Do you know if the plugs were changed, a bad or broken plug will also cause rough idle and slow acceleration?

i think #5 is on driver side the front one....

problem solved mechanic had wires on wrong thanks