L29 454 running rough...

[Daly]

I recently replaced the drivers exhaust manifold on my truck and since then it's running rough. It feels like it isn't firing on all cylinders. I replaced the plugs and the wires appear to be in good shape, but it's still not right.
Due to the current pandemic, I can't get the tools I need to test spark and fuel pressure properly, so I'm waiting for an order online. Probably have the tools next week.
What I'm wondering is, other than spark and ignition what else should I look at. I'm not getting a CEL or anything and I don't want to just throw parts at it.

Any suggestions.

 

[PlayingWithTBI]

Is it possible you cracked the porcelain on one of the plugs, or swapped plug wires by mistake? Or maybe pulled the clip inside the boot breaking its connection? Plug gaps all set before installation?

 

[skylark]

Go old school. With it running pull a spark plug wire using insulated pliers. Look for the ones that don't make a change. Then swap the spark plug with one that was firing properly and see if the problem moves with that plug. If not then your looking at a wire or firing order problem.

 

[Daly]

First thing I did was replace all the plugs. Could be a separation in the wire, I have a spark tester coming, hopefully it is something in the wire I'm not seeing.

 

[Erik the Awful]

Check your firing order to make sure you didn't cross two of them up. 1-8-4-3-6-5-7-2
I've been wrenching for nearly 30 years and I still cross them up from time to time.

 

[Daly]

Well, found a separated plug boot. I had a spare lying around. Now it runs great. It was cylinder #7, a difficult one to get at. I must have pulled the wire and not the boot.

 

[Supercharged111]

Well, found a separated plug boot. I had a spare lying around. Now it runs great. It was cylinder #7, a difficult one to get at. I must have pulled the wire and not the boot.

Similar thing happened to me recently, I'm sitting on a roached #1 boot. I had a bolt snap and the heat shield fell down and it cooked the boot. It was all fine until I touched it and then it separated.