if you excelrate slow it will excelrate without missing, or if excelrate fast, when the motor below 110 degrese. yes check for vac leakes stop at stop sign took off everything ok, stop one block and started doing it the longer it runs the worse it gets, no head gasets leaks,no valve lesks,check oxgen sencer in the exsots all four where ok,
More than likely its a weak or failing CKP crankshaft position sensor signal...
How many miles are on this Vehicle has the timing belt ben replaced ?
Has fuel filter been replaced?