RX8Club.com - Engine problem, need advice

I have searched throughout the forums and I can't seem to find a problem that exactly duplicates mine, so here goes.
My car has basically been in the shop for the past 2 months, I got it back late last week and ever since I got it back something just hasn't been right. Power seems to be ok, except for taking off from a stop. At idle it also has a tendency to stall out unless I give it a little gas. So my first instinct was that the plugs could be fouled from sitting for so long and being started up and stopped right away. So I replaced all 4 plugs, and when I looked at them they had a milky white coating on the tips of them. I had a few of my rotary buddies take a look at the plugs and we have 2 theories, either there is coolant in the engine, or its not combusting properly. The new spark plugs also didn't change a whole lot, I still get the same issue. So I took out my stock cat and put in my gutted rp cat, and while doing this I noticed the 02 sensor was only hand tightened in the cat. So after putting in the gutted cat, still the same problem. So from there I looked to ignition coils, and while doing this, I notice my air intake tube isn't even on all the way. So I fixed that, cleaned the MAF sensor, reset the ecu, and started it back up again without changing the coils. Idle seemed to be better but it was still sluggish taking off from a start. Other things that have been happening from this are alot of afterburn in the exhaust, really shitty gas mileage, excessive oil usage, and every once in a while I get a blinking CEL. The strange thing is it still starts up fine, power is still ok after about 3k rpms, and the oil looks ok from the dipstick. Now I work soon so I haven't had a chance to change the coils, does anyone have any advice? I have a pretty bad gut feeling about this, but I am hoping when I change the coils out it fixes it.