Sudden miss under medium load

[Eric Sanborn]

Coming home from work a few days ago I had to (did) accelerate briskly 
at one point.  I probably got up to 5k in 1st gear.  I don't rev this 
high all that often, but I guess I likely do ever few weeks or so.  
Immediately after I settled in at constant speed the engine had a miss.  
It kind of feels like it is alternately dragging one cylinder.  It 
happens anywhere from about 15 in Hg right up to 0 in Hg.   As soon as I 
pass into even 0.5 psi boost it starts running perfect.

The car is my 4ktq with a KH engine and KH CIS system.  I still run 
stock boost of about 6 psi.   I completely rebuilt the engine in summer 
2003.   However I happened to look at the coolant the other day and it 
looked very dark.  I have yet to look at it in good light to see if it 
has oil in it.

Has anyone had a head gasket go so quick?  Are these other symptoms I am 
having a bad head gasket?

TIA for any help.

-- 
Eric Sanborn
'85 4ktq

http://sofadog.net/4ktq/