SNG's dangerous for MTT play?

[Jurollo]

Well I preface this by saying I used to be a fairly successful MTT player, couple of win in decent size fields. However, the last two months I have played strictly PP SNGs and the Heads Up Tourneys on PS. Today I played in the $11 NL Rebuy and through the first hour was doing rather well for myself. Then the second hour came and I found myself playing too tight and after one bad beat things fell apart rather quickly, culminating in me isolating an opponent for a heads up all-in preflop with my 66 (not a solid play), he turned over A7 and caught the A on the river. Granted he was pushing with all sorts of crap all day but still I feel like my SNG strategy has really tainted my MTT game as I am geared more for the short term now than a longer format. That is why I am successful in the heads up tourney because they are individual matches rather than a long tourney. Has anyone else noticed that their SNG game has harmed their MTT game? Also, what did you do to rectify this problem? I am interested in getting back into MTT's as their is nothing like the feeling of battling into the final table and of course winning one is a tremendous rush. Any thoughts/suggestions to help me tighten up my rusty MTT game?