cyl. 5 miss fire. help!!

hello, i have an 03 v6. i keep getting a cyl.5 missfire code along with above 1000k missfire code. so far i have replaced the plugs, replaced the coilpack, replaced all spark wires, and the cam syncronyzer with still the same problem. it only occures under load or if im cruising under 2000k, if i floor it or if i'am cruising at highway speeds it dosnt act up as bad. will kinda backfire/hiccup at times and then take off like nothing is wrong, other times it bogs down so much it seems like its just going to quit on me, then it picks up again. i have noticed that i barely have any exhaust comming from the drivers side tail pipe. would a pluged up muffler cause this?

Might be time for a compression test of the cylinder and an ohms test of the injector. I would start there. Make sure there are no vacuum leaks on the #5 intake runner.

ok, how do i check the injector? or should i just try to replace it? i changed out the cam syncro. about 2 months ago do you think i might of screwed up the timing? if so can it be fixed by me or does it need to be hooked up to a computer? here are the codes i keep getting, they always say pending and erase themselves. p0316, p0305

ok ran the scanner and i keep getting code p1336
manufacturer control ignition system or missfire.
here are the specs that i got from my scanner

engine rpm- 1711 rpm
load value- 25.4%
coolant temp- 176*f
short term fuel trim 1- 7.8%
longterm fuel trim 1- 0.8%
short term fuel trim 2- 3.1%
long term fuel trim 2- 2.3%
short term fuel trim 3- 22.6%
long term fuel trim 3- -96.7%
long term fuel trim 4- 85.9%
short term fuel trim 4- -61.6%
vehicle speed- 37mph
fuel rail pressure- 264 kpag
fuel system 1- closed

so far i have replaced the plugs, wires, coil pack, seafoamed the engine and changed oil. before i got this code i kept getting a cyl. 5 missfire code. now im getting this one. any help would be great
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Check were the spark plug wire runs along the engine. If there was a vacuum leak it would run rough the ecu would pop up a code showing that you have a vacuum leak. Kinda does sound like you may have bad commpression though:( look at renting a compression tester. I got one if ud like to borrow it.

93pony wrote:ok ran the scanner and i keep getting code p1336
manufacturer control ignition system or missfire.
here are the specs that i got from my scanner

engine rpm- 1711 rpm
load value- 25.4%
coolant temp- 176*f
short term fuel trim 1- 7.8%
longterm fuel trim 1- 0.8%
short term fuel trim 2- 3.1%
long term fuel trim 2- 2.3%
short term fuel trim 3- 22.6%
long term fuel trim 3- -96.7%
long term fuel trim 4- 85.9%
short term fuel trim 4- -61.6%vehicle speed- 37mph
fuel rail pressure- 264 kpag
fuel system 1- closed

so far i have replaced the plugs, wires, coil pack, seafoamed the engine and changed oil. before i got this code i kept getting a cyl. 5 missfire code. now im getting this one. any help would be great
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Thats what i'm looking at. i'm not sure what why you have 4 fuel trims. Usually it's only long and short term trims for bank one and bank two. anyway with those numbers that high it is telling you that your dumping fuel into that side of the motor. meaning you prob have a vacuum leak, or it is seeing all that o2 cuz it's a misfire and none of the o2 is being burned up. Check for vacuum leaks and might wanna do a compression test. also a easy way to check your injetor is to swith cyl 5 injector with another cyl and see if the misfire moves with that injetor.

thanks for the replys, this was fixed months ago. it was a faulty coil pack from autozone