When should head gaskets be serviced?

[scattermaster]

Hello,
New here.
2000 Expedition. 5.4 Triton motor. about 260K miles.

I've been fighting a misfire in #8 cylinder code for a while.
I already replaced the spark plug and coil and nothing changed.
The engine is kinda hard to start, like it has a vacuum leak. (I have to switch it to on and wait a few seconds, then start it)
When this happened before, a shop said I needed an intake manifold. Replacement fixed my problem. That's been a few years ago.

SO, I'm replacing the intake manifold myself this time. (and crossing fingers it wasn't something else)
I'm pretty close to having it out as of now. All of the vacuum lines look good to me.
Anyway,
If you were doing this, would you go ahead and do the head gaskets while you're in there?
I'm somewhere around 260 K miles and the heads have never been off.
I'm not seeing any issues with the head gaskets or anything, it's just that it's quite a chore getting this far in and looking for things I should do while I'm there.
What would you do?
thx,
Jim
Edit- I have the manifold out and there are signs of it leaking air all over the place!
After looking at the heads, I'm gonna bail out on doing those. I wasn't intending on rebuilding the entire truck...
I'll probably do the spark plugs though. It'll be real easy now.
thx

 

[bodabdan]

Head gaskets don't need replacement unless they're bad.
At your mileage and while manifold is off, I would pull valve covers and inspect roller followers and lash adjusters, solenoid screens, and timing components.
If you wanted to freshen anything up the valve timing components and oil pump would be my first priority.

 

[Ellison Brown III]

When they start leaking. It’ll it ain’t broke, don’t fix it.

 

[Wangle]

I did this a few years back on my 2003. Had some pitting on the heads were the intake seal was. Filled it with JB weld, then stone smooth. Yes your spark plugs, and your valve cover gaskets. I did the alternator as I still had the original on there. That was probably not necessary. Have fun and good luck!

 

[Wangle]

Oh! And I removed the big mouse nest that was on top of the block between the heads

 

[holeintheice]

drop a scope into cylinder. if piston head is washed at lowest part. bet she is leaking, or do a sniffer test. coolant level full?