Why is my speedometer dropping at 0 when i get up to 60 mph? And my panel lights comes on saying check engine

What is your question?

I'm not hearing any noise. I just had my coil packs changed. And I changed my oil.

What makes this problem better or worse?

Only when I get up to 70 mph

How long has your 2005 Mercury Montego had this problem?

2 months