Rough idle explorer

[sicktight772]

Hello, new to the site and I just bought a 98 ford explorer sport 4x4. Its and auto with an 4.0L SOHC engine that has 125K miles on it. When I got it, it was idling really rough, from the stock tach seemed to be close to 600 rpms. I pulled codes and got
P0304 (Cyl 4 Misfire Detected)
P0305 (Cyl 5 Misfire Detected)
P0171 (System Too Lean-Bank 1)

Well I cleaned the MAF, Cleaned the IAC, and put in new spark plugs and wires. I Then erased the codes and and took it for a drive about 5 miles down the road. It was still idling rough,but not at bad, and I think I have the timing chain death rattle that I have been reading about. But the Check Engine like did not come on till I got back home and parked it while idling. The new codes are the same as above plus

P0300(Random/Multiple Cylinder Misfire)

What Else should I try to do to get this engine to idle right. I runs fine on the highway and Has plenty of pick up and go. Its just the idle pretty much shakes the whole Vehicle. Can anybody pin point some things I should look at instead to just tossing money at it, Would running seafoam through it help any?

Thanks,
John

 

[Runnin'OnEmpty]

Congratulations on the 'new' Sport, John.

Considering the age and mileage, my guess would be
a leaking intake manifold, caused by faulty upper
plenum gaskets.

If the missing is worse when the engine is cold, and
gets better after warming up, then that would confirm
it. (The gaskets will expand slightly when warm.)

There's a sticky that documents repair procedures.

 

[sicktight772]

Thank you Runnin. I'll try that next weekend when I have more time, Don't have time to do it tomorrow, but I am going to put a new fuel filter on it though, see if that helps any also. It sucks having your vehicle 100 miles away from you during the week, lol.