Don't take this the wrong way, but did you double check the gap on the new plugs before installing them?

Also, when doing a compression test, all plugs need to be out to accurately gauge the compression on a single cylinder.

 

Can any one tell me the location of the obd port on my 91 v6 ?? got to find the source of the "check engine " is this obd 1 or 2 so i know what scanner to get /thanks

 

It's OBDI, all you need is a paper clip to pull the codes. I can't remember which pins to bridge with the paper clip, but its around here somewhere. Good luck

EDIT: Here it is: http://personal.utulsa.edu/~nathan-b...85diagnosi.pdf