HELP! 04 4.0 Rough idle/ Misfire? | Ford Explorer Forums - Serious Explorations

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HELP! 04 4.0 Rough idle/ Misfire?




I have a 2004 Explorer XLT Sport with a 4.0 V6. I recently did a bunch of work on it including:

replaced front differential fluid w/ Mobil 1
replaced transfer case fluid w/ Mobil 1
replaced rear differential fluid w/ Mobil !
new Motorcraft air filter
ATTEMPTED to replace fuel filter without success
flushed and filled coolant
new Motorcraft Plugs and Wires

It was running like new for the first 100 miles or so, now it idles rough, stutters when accelerating from idle, and the "service engine soon" light came on.

I scanned the OBD II computer and it came back with:

P0171 Bank 1 system too lean
P0174 Bank 2 system too lean
P0300 Random multiple misfire detected
P0316 Misfire on start up

Anyone have any ideas? I don't know where to start. Thanks!

does it get better after it warms up? sure sounds like leaking intake manifold gaskets to me.