a few issues...

[Sconic]

hey i have a couple questions about my 86 3.8L...

First off, my car has lost quite a bit of its top speed. Now, i know its not a fast (or even close to fast) car to begin with and the speedometer only goes up to 85, but a few months back i used to be able to go well over 85 and now i top out at 77. Speedo doesnt seem wrong either. So any help with that is appreciated.

Second, when i travel on the highway for too long, i start to get steam (or some kind of light smoke) coming out of my vents. I turn vent on to blow it all out of the system but leave it off for 5 minutes and its there again. My heater core has a leak and leaks out of the A/C weep hole. Could this have anything to do with it?

Thanks for the help guys and please respond if you know anything that it could be cause im about lost. thanks again.