Driving in the highway this morning and all of a sudden my car gradually lost power then stalled.. Thought maybe it overheated but temp is normal, open the hood, everything looked okay cept when i checked the plug and plug wires. 2-4 had a bit of oil, it seems like the seal broke and leaked over the plugs..

Changing the plugs and maybe the plug wires tmrw, hopefully it'll crank and i could drive it towards home to change the seal...

Now for the question:::

Any DIY for changing the intake manifold seal? Tried the search but came up empty.. I have a repair manual book but any advice would greatly be appreciated; like say how difficult it would be? Parts needed... Thanks

Oh i have a 93 miata...

 

It is very difficult, if you're not a car service employee of course.

 

Why do you think it's the intake manifold gasket?
The intake manifold plumbing is on the firewall side of the engine i.e. on the opposite side from the plugs and ignition, and a) there shouldn't be an oil issue with it anyway because the pressure there is negative (it would suck oil, not blow) and b) there shouldn't be much oil around there anyway. From your description it sounds more like a valve cover or head gasket issue.
There's just a faint chance your PCV is blocked, pull it out and shake it. If it rattles it's good; otherwise replace it.
I suggest that you remove your plugs and see if they're dry and in good condition, and that there's no coolant or oil in the cylinders; check you compressions.
Look for signs of oil in the radiator overflow reservoir, remove the radiator cap and look for signs of oil on top of the coolant. Check the dipstick to see if there is coolant in the oil. If everything looks OK, start the engine if you can, and before it's hot, cover the rad filler with your hand and see if you feel pressure pulses. You shouldn't, and if you do, it's most likely the head gasket has blown.
Some people use a Haynes or Chilton DIY manuals for major engine work, but I don't find them trustworthy and you should stick with the Mazda shop manual for important stuff like this.
If the problem is oil from under the valve cover, replacing the gasket and sealant is not such a big deal; it it's the cylinder head gasket, it's very major, involving both the exhaust and intake manifold gaskets too, and unless it's been done recently, you should consider doing any timing belt, water pump, and accessories drive belts at the same time.
If it proves to be the head gasket, I think this is beyond a DIY job unless you have a good mentor beside you, a good set of tools (a torque wrench is a must), and lots of time to do it.
Sorry, and I hope I'm wrong, but from your description, this fits the bill for a blown head gasket.

 

Right i meant the valve cover and am hoping it is..

Did check oil signs in both rad and rad reservoir nothing cept the cylinder/plugs, no coolant present in the dipstick... Im really hoping its just a gasket and sealant prob..

Thanks again..