Nitrous, I will pull the lower trans shield and visually inspect and rotate the engine. I will also run it at night to look for any kind of secondary ignition.
The distributor cap and rotor has been pulled twice now, to make adjustments and for inspection. I replaced the spark plugs a couple of days ago, visually checked each one, put permatex never seize on the threads and carefully snugged them in. I installed new good quality wires at the same time, carefully, making sure that they are away from the headers.
I will check the brake light switch, as well.
The miss is aggravating. It's been there ever since the transmission was swapped. It got better after the distributor, and then crankshaft position sensor was repaired. Then was back two days later. At idle, the truck runs beautifully. Then when accelerating it feels like it loses power, it makes this phut phut noise, and then once I'm done accelerating or not running around 2000 rpms, it's smooth as silk again. The minute I start accelerating or am up around the 2k mark (what I call highway speed, because in 3rd gear I'm around 2200) I get that loss of power miss. It's not a jerk or shudder, it feels like all of a sudden I'm not getting fuel to a cylinder because there is a sensible loss of power.
To further cloud the issue, my stepfather put Marvel Mystery Oil in the tank right after the transmission swap because that shop recommended it. He also added it a few days ago, thinking it was helping. I swear the miss has gotten worse since it was put in my tank. No one around my area thinks it's a contributing factor, but I'm not so certain.
Should I replace the IAC or start hunting down a set of injectors? I've personally put 100k on these injectors, and have never done anything with the egr, iac, map sensor or throttle body. I'm doing my own research on the side, but I will do what you and Transman recommend.
Also, my downstream 02 sensor is right next to the transmission, and it's possible it got hit when they swapped the trans out. I mean, they hit everything else, so why not. Could a damaged 02 sensor do any of this?
