Hi, im New to this site but i got a 2000 Dodge Ram 1500 that was Misfiring and Shuddering at the same time. The misfire code was P0300(random Misfire), but i replace the Spark Plug, Spark Plug Wires, Distributor Cap & Rotor and Ignition Coil today. I Took it on a test drive went fine for about 20mins but started to Shudder.
The Shuddering only happens when i stop the vehicle at a Stop Light and when at idle speed(without pushing the gas pedal down to go), but the truck doesn't die out.


Can someone help me please?

 

Plenum Gasket would definitely cause that. Its a common thing to fix on these. At a stop you're pressing on the brake thus using the vacuum from the engine, and that plenum gasket also leaks vacuum so most likely that would cause the misfire at a stop. First buy a new pcv valve & do a tune up before you commit to the plenum gasket change. Also check for any vacuum leaks by the map sensor in front of the throttle body, that small rubber hose that connects the throttle body's map sensor to the plastic vacuum line likes to break apart over time.

 

Alright ill check =]
Ive also hook up my Trouble code Reader and it says im now Misfiring in cylinder #1 & #8, how could this be when i replace all the ignition stuff? o.O?

 

This is typical for these motor's. Got a comp tester? if yes do a dry and wet test, if no go buy one and do the test. Don't spend anymore money until this is done!

How this happens

Starts with a leaking intake plenum gasket (see the plenum sticky thread), that leads to a plugged catalytic converter, that leads to a set of cracked valve seats/heads. This results in low comp for these cylinders making for a mis-fire. So a set of new heads, a new plenum gasket set or a Mopar M1 intake or a Hughes F1 airgap intake, new cat, new 02's and you should be back up to snuff.

Edit: Plenum Sticky thread; https://dodgeforum.com/forum/2nd-gen...um-thread.html

Edit; Also see; http://dodgeram.info/tsb/1998/18-48-98/18-48-98.htm

 

Merc's case stated is the worst case scenario. But check out starting with plenum and go from there. Heads may not be bad...yet....Gotta get it corrected before it generates all that carnage. And check cat fur sure also.