Ok guys this is my first yota, it's a 1990 4x4 pickup with supp a rebuilt engine. The other day it started running funny at a stop light and acted like it was running off of 3 cyniders. Got it home and there was a strong rich smell come inch from the back near the fire wall. I'm thinking it may be a head gasket due to some water lose in the rad, but it never overheated and once you get going it runs fine. Any ideas would be great!!

 

Here we go...have you checked basic tune up stuff? pulled the plugs to look at them...you know...all the auto basic 101 stuff?

 

Do a good tune up. Don't use bosh. And make sure it's not something silly like a loose plug wire. That sort of crap would happen to me. Denso spark plugs can be found for around $10. Your motor was designed for these plugs.
I have always bought "what the parts store had". Well I have had to redo some of y work too soon for my opinion. I am now slowly switching back over to oem. They just seem to run a little better.