Coolant is supposed to have inherent anti-corrosion properties, otherwise our iron engine blocks and heads would have rusted apart decades ago. It's going to sound horrendous if there's coolant mixed into the oil. It might still be salvageable, but you would have to pull the heads off in order to fix it properly. dropping the 05 motor in with a throttle body adapter plate might be your best bet. IIRC the fuel rails from the 98 will fit over the 05's UIM, and line up with the injector holes, but I'm not 100% sure on that. Most of the other sensors are either in the same place, or aren't going to be moved over from the 05. The adapter plate you can get from ZZP for $100, and the rest should be plug and play. the MAF that is part of the intake tube for the 05 is inside the TB on the 98, the MAP sensor I'm not entirely sure on. I would keep the AC compressor and alternator from the 05 engine when you swap it in, it's just easier that way.
