car is a 77 240d with 200k mile new to me this week. paid $350
car is very hard to start .70degree day fresh battery( just off a full charge over night). battery was dead so pull started to drive it home yesterday( the car started while being pulled with in a very short distance). took full 5 minutes of cranking on & offf to get it to start today.

i talked to the previous owner & she had never adjusted the valves said that it was hard to start below 40 degrees. appears to have new glow plugs. has a 6month old battery. the air filter was extremelly oily with a puddle of oil in the houseing.
car starts well after it is warm. runs rough at idle smoth at speed with no power and very slow. car wont turn off with key nor will it turn off with the stop switch. it will run slower but not stop. i kill it in gear with brake.
2 questions
1 where do i start to get the stop switch to stop it ? seems like this should be an adjustment in the linkage right? if so what?
2 hard start may be bad compression or a combination of things like valve adjustment, fuel delivery, glow plugs. should i start with a compression test? if so how much do they tipacilly cost? & would the valves being out of adjustment affect the compression test? THANKS FOR YOUR HELP JOHN M