Yes, bad idea. Please try to stick with your 70mg and stop the dope for a week and two and see where that puts you. If your dose is still getting you high, 70mg is not a whole lot so the euphoria will diminish over time, DO NOT CHASE THE METHADONE HIGH!!! This is one of the BIGGEST mistakes made by people at methadone clinics, including myself the first time around with methadone, and PLENTY of people that I know. It is not worth it. In the end I was on 145mg not feeling a high AT ALL, I was a worthless lethargic piece of shit, and even if I took a double dose (one of my take homes) and ingested 300mg of methadone, it still wouldn't get me high. No need to chase it, because it's like any other drug, chasing the high is chasing a twinkie on a string while running on a treadmill.
If you
absolutely have to, raise your dose to 75mg after a week, but none more. And do not go over 80mg. You're being adequately treated.
I want you to look at this chart of methadone maintenance administration and read the levels of medication and their description so you KNOW what you're trying to achieve. It's a page I found while browsing on my phone within the past year ago, so it's a screenshot from my phone.
http://i1033.photobucket.com/albums/a419/dmlee2421/mdonelevels_zpsf1fcdea8.jpg
OP: Look specifically at the top two entries in the chart (therapeutic comfort range, and overmedication symptoms and signs, you'll see you're exhibiting some of them according to what you've said), but please do read the whole thing. Will take a minute.