I searched, but could not find anything quite like this:

I have a 1998 Toyota T100 (V6) with 260K+ miles on it, typically runs like a top.

It never does this when it is cold, but if I start it after it has been running within the past hour, it runs very rough. It threw a code P0301 misfire on Cylinder 1.

I bought a new coil pack and plug (I didn't replace all because I did that less than 3K miles ago). I moved the coil pack for 3 to 1, replaced the plug in cylinder 1 (even though it looked fine), and cleared the code. It still ran rough, so I drove it around for a while hoping it would throw another code, but it never did. I gave up for the day.

Next day, ran great when I started it. Drive it, shut it off, restarted in about 40 minutes, ran like crap, drove it. Now it throws P0300 Random cylinder misfire, P0301 Cylinder 1 misfire, and P0303 Cylinder 3 misfire.

Cylinder 4 is also controlled by the coil pack on cylinder 1, so that kind of makes sense, but why is the coil pack that worked fine on cylinder 3, now throwing a code on cylinder 1.

Have driven it twice since that time. Each time the truck had plenty of cool down time and each time the truck ran great.

Any idea what to look at next?

Thanks,
Sam

 

Can this be an indication of an injector issue?