im having a hard time figuring this one out. my truck has a misfire that is very noticeable at low rpm when in O/D the truck will buck hard and seems to lack power. I haven't gotten a code but I got it to throw a pending code sitting in my driveway I found the sweet spot where I misses a lot and held the gas there for about a minute and got p0300 random multiple cylinder misfire. so far I have done:
-new plugs
-new wires
-new cap & Rotor
-new Accel supercoil
-new PCV
-new PCM
-fixed multiple vac leaks fuel trims are showing good
-new EGR feedback solenoid
-blocked off EGR
-new fuel pump
-new fuel filter
any help would be appreciated!!!!!!!!

 

Clean the MAF sensor and check for vacuum and exhaust leaks, there cannot be any leaks in the exhaust upstream of the primary O2 sensors or in any of the thermactor air injection plumbing. I'd also suggest testing the fuel pressure just to be complete.

Your symptoms sound like a global lean problem which suggest something is causing the computer to not deliver enough fuel, if the motor doesn't stumble right after cold start this diagnosis is somewhat confirmed. If you can get a scanner to look at realtime sensor outputs you may discover what is causing the problem.. like a temp sensor that works but is reporting the wrong temperature or a MAF that is out of scale.

 

thanks for the reply conanski, i did have a leak in the thermactor crossover tube that i repaired but aside from that no leaks i also have tested the fuel pressure and its good. the motor does stumble a little after a cold start but just for a second. i do have a scanner and have looked at real time data, my o2 sensors are cycling properly and my fuel trims look normal(usualy stay at around 0 to 2 but have seen -3 to 5, i have also cleaned the MAF and looked at the data but am not sure what it should be my scanner reads the airflow in lbs/s and at idol it will sit at .02 and go up as i apply throttle. do you know if this is correct?

 

OK if you do get a stumble at cold start then the problem may be something basic like cross firing between plug wires. I notice you have a super coil, this can amplify this problem so you need to make sure the wires for 5&6 are separated and that all the wires are insulated from metal engine parts. I cool test for this is to startup the motor in complete darkness and have someone goose the motor or apply gas and brake while in gear while you look for cross firing, if there is any you will clearly see the light it produces. This could also expose a faulty wire, most often the fault will be at one of the connectors.

 

first off, if wires and everything else in ignition isnt accel performance, take out that coil.

Also time and time again I have heard of those coils being crap, in fact nobody buys them at work because the suck.

Personally I would have left EGR alone, ive heard these trucks dont really benefit from a delete.