Whats wrong with my truck? on 1991 Chevrolet S10 Blazer

I have a 1991 S10 Blazer 4x4, with a 4.3L V6.. it has 193000 miles on it, but it
has been well kept up. It was running just fine until one day recently I was
drving down the highway and it started jumping. Then a few days later the
blazer, began popping and jumping very badly. It wouldnt stay started if I took
my foot off the gas. Now it has a VERY rough idle, where the entire truck
rattles and shakes..I cannot start it and move it, because just as soon as i
take my foot off the gas, it begins to sputter then dies.In the middle of all
this it also overheats, and smokes after running for ten minutes or so...Which
it never did before the sputtering, and jumping,etc... I have had this vehicle
for two months and it never did this until just a couple days ago.It was a
strong running truck. I would really like to fix it because it is my only
transportation. I have no idea what it could be. I know that it was given an oil
change, but we have since had to have more oil put in it beca
use the oil filter housing has a hairline crack in it which causes it to leak..
The only other problem I have is a faulty gasket on the transmission pan... But
it was runnning great until all of this came about...

Asked by for the 1991 Chevrolet S10 Blazer
1 answer 3 comments
the fact that you said it overheated makes me think you blew a head gasket and that would explain the missfire and smoke. you need someone to do a leak down test to verify.

I believe you are right, because we drained the oil and it was milky-brownish-white, and thick as lotion.. Does a blown head gasket describe just about everything that was wrong with it? Also would this make it hard to start?
yes to all. fix the head gasket issue first and see what happens.

thank you we will try it and let you know