ECB Unusual Problem ...

Ok my first post here ...I have been smoking for just long enough to know what temp, and how long I like to smoke certain meats, however, the WSM that I have been using is my father-in-law's and I had to return it last week. My wife didnt want me to drop the $$$ on my own so I decided to use an ECB that a buddy gave me and heavily modified her. I bought a cheap grill at walmart (Smokey Jo knockoff) and use the charcoal grate out of it raising the coals out of the bottom of the pan, drilled (8) 3/8" holes in the bottom (which can be closed with a vent that I also added) and 6 around the outer edges. I have also reversed the legs, added a vent to the lid, and sealed around the rim. I picked up a wireless grill thermometer and stuck it through a couple of corks so it would rest on the grill rack for an accuate "at the rack" reading. I know the ECB are not the "Cadillac of smokers" and have a rep for not keeping temps high enough, but my problem is IT IS TOO HOT ! Using the minion method, I started the coals, threw the water pan in, placed the thermometer and walked away. I set the monitor to alarm when it reached 230 (right about where I liked the WSM to hang out) and in no time the alarm sounded, and the temp kept rising .... all the way to 285 and stayed there until it started to cool off about 2.5 hours later ! When it started to cool it was a slow gradual decline in temp (down to 210) until I went and changed the pan out and put fewer bricks in (thinking I just put too many the first time) only to get the same temps with a shorter hold time ... I am still fairly new, and I am sure there is a simple solution but I am stumped... I know the first step in getting help is "admitting that you have a problem" ... in my case it may be that I am broke and cant buy a decent unit ... but I would love to get this thing rolling. I have talked to many people who have smoked some GREAT stuff on 10 year old ECB's, and dont see a reason why I cant .... RIGHT  ?