1998 coil,wire ,plug question=-

1998 210,000 miles, 3.1.litre.
Always ran great. Replaced wires and plugs with delco 1 year ago.
Recently started missing at almost all speeds including idle.
Is it possible if finding a no spark on a spark plug to use a different plug and wire to confirm it is a problem coil?
Does a dirty injector have the same feel?
What would you guys do?
Thanks for any advice.

Try using a different plug and wire before replacing the injector. Normally if a coil is bad both plugs will quit firing.

Get a spark tester and do a coil output check......

replaced wires and plugs.
plugs highly worn with only 20,000 miles .
car ran fine on the street up to 40 mph.
then jumped on interstate and car blogged down quickly.
,missing,etc.,with ses light occasionally flashing.

turned off engine and car will restart ,but ses light still on.

shady tree mechanic don,t want to use any kind of spark tester ,etc.
he says it,s 100% wires and plugs from his experience.

mechanic installed one new coil and it seems to work.
drove on the Interstate up to 75 mph and no misses anywhere.
mechanic cleared the ses and it didn,t return.
thanks for the advice guys.