I've got a 94 Ply Acclaim, 43,000 miles. It started to go through big swings in the temperature gauge and then I noticed i was going through a lot of coolant. i checked all the hoses and related systems, and no leaks. Finally the engine started missing badly at idle, and then also on the highway. I pulled the first spark plug and i can see coolant in the cylinder. I did an oil change within the last six weeks and the oil was fine, no coolant in it. I'm thinking head gasket or maybe a cracked block.