kia sendona van 3.5

Maybe is there a check engine light on? in neutral when accelerator is pressed is there a dead spot?

yes the light is on, scanned it and it said: primary and secondary iginition problem, and knock sensor. No re: the neutral. When you are going down the road at 35 mph it will start missing and then there is a dead spot in the throttle.

Think you need to find and repair ingition fault and knock sensor

these are the codes that the scanner has been throwing, 300-cylinder misfire(random), 302 cylinder 2 misfire detected, 305 cyliner 5 misfire detected, 350, 325 knock sensor circuit fault, also said primary and secondary ignition, does this help any with the diagnosis? I dont quite understand your reply with the "find and repair ignition fault and knock sensor", thank you

Please post all codes it will help. Multiple misss MOST difficult to diagnose.so how old are plugs,wires ect.fuel filter any recent repairs? any info will be helpful.

All the codes I listed were PO 300, 302,305,350,325 (sometimes 325) the plugs were replaced 1 week ago. no repairs other than the plugs being replaced. And the vehicle runs ok until it has been ran awhile and the engine warms up, and you hold the throttle in one position of a while then the misses begin and dont want to go over 35 mph.

Suspect coil for cylinders 2 and 5 is the fault would account for all the codes. if not then wiring from ECM to coil would be the problem

These motors are well known for bad ignition coils