my truck is a 97 k1500 with a 5.7L 350 vortec with a little over 200,000 miles on it and we did a 5 hour drive home today after i changed the oil yesterday and it ran great all the way until the last hill i lugged it just for a second comming up the hill the service engine soon light started blinking i down shifted and it went solid i took it to autozone as fast as i could and had the codes pulled and it said miss fire on cylinder 3. it has done this a few other times in the past few weeks and it only happens going uphill when its starting to lug then the light turns off in about 45 minutes. i pulled the plug and ti looked good i tested it for spark and it was good put it back in and the light went off. is this just the plug fowling a little bit when its under load and being able to get clean again or am i looking at a bigger problem? and is there anyway aside from never letting it lug to prevent this it didnt do it ever until about 3 months ago.
any thoughts help. and thanks for your time.

 

If i were to go ahead and replace the cap, rotar and distributer would this be something a guy with moderate knowledge would be able to do or should i have a shop do it? and if i were to do it myself i would imagine it would have to be retimed. i have been told that with this truck it has to be electonicaly done is this true or can it be done with a timing light? thanks for your time

 

I'd look at the spark plug. Since it is only that cylinder, check, and replace all them if they have 80K or more miles

 

sorry i forgot to put that on there i pulled the plug before i posted and it looked fine. they only have maybe 40k and they are good ac delco plugs. i ended up pulling the dis. cap and cleaned and checked the rotor it was really dusty but no cracks or chips there was a little charring on the peice that tab that sticks out so i gently scrubbed that off with a wire brush put it all back together and and the light went off and all seems well now. this might have been the whole problem but im not sure. if anyone thinks this is a syptom of something else im glad to hear your thoughts.
thanks for for time and replies

 

If it happens again move the plug to a different cylinder and see if the problem follows it

 

Thats a great idea thank you