As I'm not really sure which plug caused it this time, I've included the pictures of the plug I pulled the LAST time this happened. Replacing that plug (came out of #4) "fixed" the problem until now. Replacing the plug in #4 this time made it worse (or so I thought) and last night I put the plug that had been in it, back in. It didn't get any better, so I'm pretty sure it had nothing to do with #4 this time around. So anyway, here's the pictures of the #4 plug from LAST time that made it better by replacing it.
So, it has problems at multiple ranges. Let me see if I can describe all of those situations with some clarity.
When the engine is cold (even more some in cold weather) it just runs like crap...idle, under load, whatever. It DOES seem to get worse when it's under load but, is it just more noticeable? Maybe. Once I get up to highway speed it seems to get marginally better.
When the engine get's to running temp, it definitely smooths out but stil misses. In that case, it misfires randomly (not running rough anymore). When I lay on the gas I notice it the most. If I'm cruising or get above about 2,500 RPMs it smooths out. I'm betting that it's still misfiring, just not as noticeable since the rest of the cylinders are producing so much surplus power at that point as well as the inertia of the engine would tend to mask the misfires.
I sprayed starter fluid to every part of the intake manifold & hoses that I could get to last night. No rev. It was dark & I was ready to get to bed, so I may not have gotten it good. I'll try it again this evening when I get home from work.
Yeah, I read your thread (along with countless others, 6 hours on here Monday night). Do you remember how much it was? I looked on their site when I saw your thread & they had all kinds of different tests with different prices. I see the price list here.
And then I'm assuming all I really want is the Standard test? Did you get any of the extra tests to determine AF getting into the oil? I checked the AF level this morning & it looks good.
I reset the computer last night to see if I could get it to throw a code. I'm not sure if it will, seems like the truck has to be about to die before it'll indicate a misfire.
I definitely appreciate everyone's help...this has been a phantom for some time.