rough idle in 1998 ford explorer 4.0L v6 sohc engine

[slums77]

year: 1998
engine: 4.0L SOHC v6
model: Ford Explorer Sport

so today I went to start my car this morning, and it was kind of cold outside. I started it and it shot up to around 2500 rpms or 3000 rpms but then it would bog down real low past its normal idle frequency and it would sound like it was gonna stall. It repeated this many times but it never stalled. I've never had this problem before and my car had no problems starting and running last winter. does it just need to warm up or what? I have recently replaced the oil filter and oil, so I don't think its that problem. could it be a leak? I heard this rough idle thing is fairly common in the single overhead cam engines....so could someone please help me out? I really have no idea where to start. (please include prices so I can get an estimate of how much I might have to spend)

UPDATES:
-the whole car did shake while it was at the low rpms
-could it just need a tune up? new plugs, wires, air filter, etc.
-new pcv valve?

PLEASE HELP!:yelexp:

 

[slums77]

come on guys...will someone please help me out.

 

[signguy35]

fuel filter?

 

[2000SportDennis]

When's the last time it's had a propper tune-up?

 

[slums77]

not for awhile. the only thing I have done to "tune" it up is a new serpentine belt, oil, and oil filter. is this a problem?

 

[2000SportDennis]

I would recommend doing a complete tuneup:

Fluids - oil, trans, coolant are priority (you said you did oil though); differential, brake, power steering not as critical but if you can, do

Filters - oil (done), air, fuel, trans (if AT)

Ignition - pluggs, wires, coil (local shop can test coil function); this category will most likely be the biggest help for your problem

May also want to consider new hoses and thermostat

Am I forgetting anything?

 

[lil'mounty]

I had a similar issue with my 5.0 and a friends six ranger, cleaning the MAF and the Idle Air Control Valve cured both... Now I do them every fall regardless.

 

[2000StreetRod]

possibly leaking intake manifold gaskets

It could be that your upper or lower (or both) intake manifold gaskets are leaking. If the idle is significantly faster than normal for a cold start but normal for a warm start then its a good possibility. Do you have any way to read your fuel trims?