I've lost draft!

This weekend I decided to go ahead and clean the stove and chimney good. For the stove, I removed the ash and then took a air hose to all the air inlets. For the chimney I ran the sweep through twice, although the first time did the job, and cleaned the rain cap. I then removed the stove pipe from stove to chimney. The set up goes like this for the stove pipe. At the stove it starts with a 45 elbow then about 3 feet of straight pipe until another 45 elbow and from there about 2 feet of horizontal to connect to chimney (horizontal has a slight increase in elevation going to chimney). Problem is, now the stove will not burn. I can get it to about 250 and then it tops out. The only way for a fire to burn is with the door open. The wood is the same as I've been using (so so elm). Our stovepipe is the snap lock kind and being that it doesn't form a nice circle for a seal at joints, and before I was using some high temp squeeze stuff to seal the joints, but I have since misplaced it to do it again. Is it possible that there is enough leakage around the stove pipe joints to cause significant draft issues? Another question, does any one have any opinions on what you think is decent stove pipe (especially for how it seals at the joints)? And has anyone ever used flue tape by 3M to seal the joints on their pipe? Here is a link to the tape http://www.amazon.com/3M-2113NA-High-Temperature-15-Foot/dp/B00004Z4DS

As of now, no IR thermometer. Hopefully soon tho. As far as pipe leaks go, I would assume this is normal for a snap lock type stove pipe? I don't have a smoke coming out of the stove pipe or anything of that sort, my concern is more based on just the fact that the pieces aren't that airtight at the joints due to the type of pipe. I have looked online at some of the welded seam pipe and I would assume that those form a better circle (seal) since they come from the factory in pipe form. But not sure if they are worth the extra investment. The stove pipe is the only thing that I believe must've changed from the cleaning that would might not have improved the performance just due to the fact that the sealant on the joints is no longer there. But I don't see how there could be that much draft being used up around the joints to cause the wood not to burn.

Jtb- when blowing air through I went both ways just to make sure. But I would imagine that that would be a pain if you ended up with a clogged air inlet. I can only come to the conclusion that the joints in the single wall stove pipe are using up the draft that the stove needs due to leaky joints. I am going to try the flue tape (tho only rated to 600 degress) and see if that helps, if it does then eventually will just install the welded seam type stove pipe for a snugger fit.

The chimney is a class "a" stainless double wall. So all the fittings are interlocking. No chance of anything being pushed too far. The clean out is also just a twist lock cap at the base of the pipe. I don't think it is because of coals either but I could be wrong. But on the 30tnc it has an air port that shoots air from something that sticks up at the base of the door, but since the cleaning that air inlet no longer is shooting air in. I could always tell before because if a log was placed anywhere in front of it, it would burn a hole right through it from the air shooting out. Now there is nothing coming out of it from the looks of the splits in front of it. That is what lead me a draft issue.