Raub

Hi all, new member here. Just bought a 1990 V6 Extended cab pickup over the weekend. It ran fairly well when I bought it, save for a leaky exhaust manifold. Saturday I started a tune-up...changed the oil, put on new cap and rotor. When I started it back up it ran like crap. Would barely idle, didn't want to throttle up. Exhaust smells REALLY rich. I've started going thru some troubleshooting steps, checked all the vacuum lines, and checked the troubleshooting codes in the ECU. ECU is only giving me code 55, so no help there. I pulled the coil, and the primary resistance is 1.4 ohms. The manual gives a range of 0.7 to 1.0 ohms. Would 0.4 ohms out of range cause it to run very rough like that?

Any other suggestions are welcome. I'm at a loss. All I did was install new cap and rotor and change the oil. Afterwards I went ahead and replaced the plugs too. It had Bosch +4s installed and I've never been a big fan of them. I correctly gapped the new plugs and am getting spark to each plug. Just wondering if it might be a weak coil. Thanks.