Engine off after warm up and wandering at interstate speeds

Wondering if this is just my car or something thats common with the Gen 1? After my car gets warmed up, just over 150F, the first stop or coast the engine will shut off. But unless I stop again and wait the 5 seconds or so for the engine to stop, I can't get it to shut off again down a hill or coasting. I need to stop, let it shut off, then after that all is good. Lift foot, engine off. Drives me nuts when I have a long hill and it doesn't shut off! (I'm using a scan guage II to watch the rpm and water temp)

Also a question on the steering, we took a 550 mile trip this past weekend, all interstate. Although it was a little windy, the car takes constant steering input to keep it in the center of the lane. It did get old after that many miles! Common problem? I read a little on the Gen2 having problems like that but the solution was dealer adjustments. The previous owner did have a new rack put in in 2008. Anything a DIY'er could do?

Thanks!
Gerry