87 suzuki samurai 1.3

My samurai only fires on cylinders 3 and 4. There is some oil deposit on the spark pulgs on 1 an 2.
The engine still runs but has no power.  The cat also after running for a while will start to glow red. 
The spark plugs do spark. Any ideas before i remove the cylinder head and do more troubleshooting?

Usually if the Cat is glowing as you have indicated. This causes the lack of power that you are experiencing. Doing a compression test to see the condition of the motor 1st before replacing the Cat would be a good idea for a base line.

The C/R should be at least 150PSI or better on all 4 cylinders.
Double check to be sure that all 4 plugs are getting spark.
Pull the plugs and ground them and crank the motor over and verify the spark.

If all that checks good then replace the Cat.

Just My 2 Cents

i have done a compression check all cylinders where exactly 150. i checked the spark plugs one hour ago and they all have spark.

Very Good. Go ahead a change out that clogged Cat and you should be good to go.