I know it's been awhile since my last post but I changed my PCV valve. No change. The missing seems to be consistent to the engine running as if 1 cylinder is not firing. Maybe a valve is not closing all the way and loosing compression? Would a loose timing chain cause this? Also i have noticed that when i am driving and come to a stop, around 5 mph just before i stop the engine seems to stumble more.

 

First off, to check for a cylinder misfire pull one wire at a time from the coil pack and listen for a change in the way it's running. This will let you know not only if there is a misfire but which cylinder/s it is. (do not touch frame while you do this, you will get a jolt youself) If there is a misfire this will help you troubleshoot the issue. You may even find that when you pull a wire that there is no spark and will answer you question right then, you don't know till you try. Just pulling the wire for a few seconds should not throw a code so you don't need to worrie about clearing any.

I'm not sure if a misfire will cause a rich condition. Rich and lean conditions are triggered by a combo of the 02 sensors and fuel trims. If the 02 sensors arn't happy with the fumes for the cat., it tells to computer to add or take fuel away. High trims = lean (to much air getting into motor and trims can't add enough fuel) rich (trims can't take enough fuel away possible because not enough air is getting in). Depending on the size of the leak (if any) spraying carb cleaner or another flammable arisol will not always make a difference in the motor. With todays computer control, the computer can make ajustments fast enough that without a live read out, there is no way to tell. Example is I know my intake gaskets are leaking but without my scan tool and live data, I would not know that. When I spray the area I see the trims sink because I am adding the fuel so the computer don't need to and when the trims get too low the IAC allows more air to enter keeping the rpms to same.

One thing also you might want to check which I didn't see listed is the fuel pressure. If you got a pump that is starting to go, it could cause problems. Gauges are fairly cheap ($30) and I believe you should have a test port on the bank 1 side (passenger) with a blue cap on it. Double check the specks but I bellieve it should be betwen 35 and 65 psi, hold psi key on engine off and when running, maintain current psi with no drop when fuel is given.

 

Thanks for the reply. I sprayed carburetor cleaner around the intake manifold, vacuum lines and any were that might be a leak and no change. I also pulled the wires from the coil pack to see if there was any change in the engine speed and there was change for each cylinder indication that each cylinder was getting a spark. There is a loud ticking noise coming from the driver side of the motor like the rocker arms are out of adjustment or worn. Some one told me that that can cause a lean condition in one cylinder. At the exhaust pipe you can here a popping noise, kinda like it's blowing air, and it is consistent with the engine speed. So maybe 1 cylinder is not getting enough fuel, possibly the valves are not opening far enough?

 

With todays computer controled engines, it is possible that spraying carb cleaner will not show a vacuum leak, my didn't. For me it took me using a live scanner showing the fuel trims to find mine along the fuel rail. The only time the motor stumbled was when the trims started going negitive, which was 1/2 to 3/4 can later on the area. One thing you can try if you don't have access to a live scanner is disconnect the battery for a few mins, this will reset everything including the trims, a vacuum leak may show itself then. You said the intake manifold gaskets were replaced, they might not have changed the o-ring from the egr tube into the manifold, check that area out.

Test the function of the egr valve. You should have a vacuum line in that area that is connected with a coupling. Disconnect it and replace the vacuum line from the egr with it, this will open the valve and should cause the motor to stall. If you can't find a vacuum line from the motor to do this, use something that will pull a vacuum to do it. Also to make sure that the valve is closing, you can apply a small amount of pressure to the valve, say 1 lb or so.

I can't answer about the rocker arms but it sounds like a compression test is in order.