1997 LeSabre with a 3800 SII non-supercharged

just did the LIM gaskets, Dorman upper plenum and everything that goes with (fuel injector o-rings, pcv, etc. ) plugs (NGK TR55IX) wires (Delco) and a coolant flush/replacement with new hoses/thermostat, etc. Used green coolant and flushed out the orange. 180 degree thermostat. I also had to replace the coolant temp sensor because I accidentally broke the old one by dropping the manifold on it (durrr...)

WHAT THE CAR IS *NOT* DOING:

-starting hard (fires right up)
-idling funny (purrs like a kitten)
-overheating (temp is perfect
-smoking or having any weird stuff out the tailpipe

WHAT THE CAR IS DOING:

-running a bit rough under anything more than slight throttle
-bucking just a bit (not violently) under harder throttle. It'* more like shaking a bit under throttle than real bucking.
-occasionally get a *pop* out of the exhaust when it'* bucking/shaking.

It threw a CEL, and the computer at the Checker said #6 had a misfire detected.

I made sure that the fuel injector was plugged in, firmly seated in it'* bucket, and I tried a new plug and made sure the wire was attached properly. It seems to be fine at idle. Purrs nicely at idle, but if you remove wire #6 the idle turns to crap, so I think there'* fuel and spark. It cetainly acts like there'* a 1-cylinder miss at throttle though.

Is it possible that injector #6 went bad while it was out of the car?

Help is appreciated, as ever!

have you checked to see if is the plug wire hitting the 02 or 02 Wires by chance, i just fixed a GTP with a p0306 yesterday, with the same symptoms

It isn't.

For some reason, none of the wire clips are present on this car. Whoever installed the last set of plug wires used zip-ties. Still, nothing'* hitting anything it shouldn't or anything odd like that.

I've got spark to the plug.

If you suspect a bad injector on cyl 6, try swapping it with another cyl to see if the problem follows.

A misfire like this can be a symptom of coolant ingestion. I know you said you just did the UIM / LIM stuff...are you absolutely certain that every bolt was torqued down properly? Did you install the TB gasket (it'* been forgotten by more than one of us )? Is your coolant level in the overflow now steady?

Derp. I had the throttle body gasket installed...yes...but the top nut was worked loose and I had a massive air leak.

Dar Dar Dar I'm a tard. Thanks for the help everybody, much obliged to ya