After repairing a vacuum leak, my '92 Dakota V6 had consistently been returning about 21 freeway mpg. But when I drove it to Michigan last month, it's mileage was 19 mpg at best. I changed the spark plugs in Texas last week, replacing Bosh Platinums with Champion RC12YC Copper Plus plugs, but while performance improved, gas mileage didn't. I also replaced the driver's side valve cover gasket because the mechanic who replaced the rear freeze plug said it was leaking oil. The old gasket wasn't cracked anywhere, but gasket glue had accumulated around the bolt hole near the #5 plug. Maybe the oil stopped leaking, but it's still losing a quart about every 1500 miles. Time to replace the PCV valve again? The cruise control had been going flaky, occasionally cutting out and even not setting, but after the plug and gasket replacements, only resume won't work, which seems to be a switch problem. I squirted electrical spray cleaner into it, but no improvement. A glitch developed: when the speedometer is on 70 and showing 2200 rpm, the truck is actually going about 67 mph. However, driving through Arkansas, I noticed that the tach read 2400 rpm at 70 mph. A quick calculation (48 seconds between mile markers divided into 3600 seconds in an hour) determined that 70 was actually 75. This returned to its normal reading of 67 for 70 after I stopped for gas, but rose again after another stop. Don't know what this problem is, but I'm leaning toward greasing the speedometer cable, even though it's not making any noise. Another glitch seems to be related to very cold weather, as it's only occurred in Michigan. The shift point from 1st to 2nd gear is usually around 15 mph or less, but here, it occasionally goes to 20 mph, and well above 2000 rpm, before shifting. A mechanic said that this could happen if the fluid in the torque converter isn't warm enough. I'd like to change the trans fluid and filter soon, as it's now over 45K miles since the last change. The cheapest ATF+4 I've seen is around $4.25/quart at Wal-Mart. Do any retailers sell ATF+4 in gallon jugs for less than $17? Also, how can I tell exactly what transmission I have? From what I've read, 3 separate automatics were available with the Dakota V6 in the early '90s. On the way back home 2 weeks ago, the headlights cut out twice at night, though they came back on soon afterward. I replaced the headlight switch with one from a junkyard, and so far, that problem hasn't recurred. Yesterday, I cleaned the crankcase breather. According to the shop manual, it should first be soaked in kerosene, but I didn't have any, so I used gas. It didn't say how long the soaking should last, so I left it for about an hour. After that, it said to fill the breather from the bottom side with straight 30W, then tip it to let it flow out, but again, I had to use a substitute, 10W-30. The breather didn't seem very dirty. I also added a small can of fuel injector cleaner yesterday. Too early to tell if that will improve gas mileage.