2003 Sedona Lack of power

I have a 03 Sedona with 70k miles, i have a problem with lack of power, feels like there is a considerable lack of power specially when i go to passing gear its like nothing is there as far as power, very hesitant and loggy, can hear what sounds like spark knock, have tried mass air flow, checked spark plugs,coils,added some k100to deal with ethenol, any help would be great just dont know what way to go next, please help need the van for a long xmas trip and i just dont trust it now the way its running thanks in advance
Merry Xmas to all

Have you had the timing belt changed recently?

no have not had the timing belt replaced, could of it jumped time, but then i figure there would be damage to the head, i have heard such good things about theese vans, Im thinking of biting the bullet and bring to dealer unfortunately, Any ideas let me know, I did get the check engine light to come on briefly and after checking it cylinder 4 missfire, not sure why!!!!

OK, first thing to check is the exhaust. It sounds like one of the warm up converters might have blown out and is clogging up the rear converter. Drop the pipes from the manifold and look up into the bottom of the manifold, there should be honeycomb converter material in both and it should be very noticeable. If there isn't any you should replace both warm up converters and the main converter.

Thanks RahX i dropped the sedona off to the kia dealer for a $99.50 diaga fee, they look at it after a week or so tell me to start with a full tune up aprox $1g and if it dont take care of it most likely a converter, They also said kia would not cover the converter as it had a history cylinder 3 misfire code and they contribute this to the converter problem, No warranty, never heard such a thing i had a GM impala it was under the mileage allowed for converter replacement and no question GM took care of it, Dont think i will ever buy a kia again, so much for their warranty policy, I do understand rules and things but what a line of crap,,,,,,,,,,,,,, they did mention cylinder 3 so it would be the rear manifold cat, and main cat any idea what this would run to fix if i were to tackle the job myself let me know thanks again and happy new year LOL

Did you ever have any misfire problem or have it worked on for a misfire? To me, if it is a history code and you haven't had any CEL, then a history misfire could have been a touch of bad gas or something unusual. At any rate, bitch bitch bitch. Work your way up the ladder and don't take no for an answer. Prove you have done the maintenance. They should welcome the warranty work, it is pretty much guaranteed money coming in the door. If they don't want to honor the warranty then they don't want any of your business ever. Let them know that. As far as the warm up converters go, they are kind of a pain in the ass to change yourself without a lift. It disconnects from the manifold from the bottom. I think it is about 5 or 6 nuts that hold it on and I would replace both front and rear at the same time regardless. If you only replace one of the warm up converters, the other is likely to go out and then you are going to have to pay to replace the pipe converter all over again. The pipe portion is pretty easy.

on drivers-side front of engine,,,there is a cannon plug which connects coil packs to ecm,,,this plug looses conductivity to coil packs,,,, scanning will show cylinder mis-fire try un-plugging and plugging,,,if problem kinda goes away,,,,cut connector out and hard wire the harness there,,or replace with spade connectors...my 02 does the same s**t.....this was one of the problems.....gbaum