knocking noise and possible miss fire

greetings to day my 98 sport developed knocking sound,the engine started idling rough at the same time.when idling the motor never moved now it is visibly shaking not a lot but some it did not do that be for.this leads me to beleive i also have a miss fire.although check engine light is not on i have read about loose flex plate bolts but because of the rough idling i am thinking it could be some thing else.my mechanical ability is vary limited any help or advise would be appreciated this is a high mileage motor over 300,000 miles i am afraid to start it oil pressure is normal and engine did not over heat when this happen engine had only been running for a few minutes i was pulling a small bush out in 4 low if it matters

thank you for the help

when was the last time it had a good tune up (with quality parts... avoid cheap crap imported parts)?

Did you try seafoam-ing it? Make sure to get some through the idle air passage, or remove and clean it.

check for vacuum leaks, intake leaks, exhaust leaks, disconnected sensors,
then clean all of your grounds
then clean every sensor connection
then sea foam in the intake and gas tank
then clean the throttle body real good


after that change plugs/wires/cap/rotor/o2 sensor

Test coil, TPS, CPS- replaced if needed

I would imagine after that you should be in decent shape again.