Coolent leaking into intake?

[SmokinStangGT]

I was trying to time my mustang about a week ago and it sounded and ran good, then after i bit of driving it started to run crappy and tries/and did die out after it gets warm for a few minutes... now i took a compression test and it was about half the compression it should be and when i got it running it was at as much as it should be and then after a while (when it started running crappy) and then now it is half that compression. so then i drained the oil and come to find out i had almost all my coolent in there too! so i was thinking i blew a head gasket but it didnt make sense because i had high crank case pressure now and so i went to take off the lower intake to get to the heads and the LOWER INTAKE BOLTS ON THE LEFT WERE LOOSE! I know i tourqued everything down and so i tourqed it down real good and tried again..... did an motor flush and flilled the radiator with water for the time being and put oil in.... now it ran like a champ again! But then yesterday it ran crappy so i thought i had a head gasket bad because the compression was down again too... so i went to take off the intake (lower) again and the left bolts were really loose again! so my question is if the lower intake bolts on the left are not even hand tight could i get coolent into my oil through the under part of the intke or "valley" and how can i keep these bolts from backing out again????? this is a huge pain! Any comments welcome! THANKS!