Alright i got a 2006 Accent, it has 100k miles, when its at idle or driving it sometimes stumbles. but sometimes dosen't. There is no check engine light. ideas???? It also gets worse when ac is on.

Heres the only ideas i haveadd more or tell me im wrong on some of these

Coil packs
spark plugs
PCV
TPS(would it send code?)
Fuel pump/filter (where is valve to check pressure? and how much pressure should it have?)

anything else.......

 

If there is no codes, first verify the "check engine" light is indeed functioning by turning on the key and looking to see if it lights for a few moments. If it flashes ok, then take your car to Autozone for a free code scan just to verify there is no trouble codes. If there is no codes, then the likely problem is fuel starvation. The logical next step is to do a fuel pressure check, but to do that you need a special tool. Have you ever replaced the fuel filter? It's probably a good place to start.

2006 > G 1.6 DOHC > Fuel System FUEL PRESSURE TEST

 

Yup i got a fuel pressure tester, but where on the car is the valve to test it?

Also what do you guys think about the pcv or coil packs?

 

Coil pack would generate a code.

It could be PCV, but only at idle. Take the PCV off and clean it.

 

ran into same issue on my brothers 03 accent and it was that the one of the coil packs were crack. Spray all over the coil packs with a white lithium grease. also clean all your ground wires