My understanding is when the P2.5 was released it increased the amp limit to 3.5a. I wont wager my life on it though. 
And yes, I will realize some resistance fluctuations too. Not so much with 28 gauge but definitely with 30 gauge. Never could figure that out. Sometimes it would fluctuate up and then return to the original level. Sometimes it would gradually increase over time. My 28 gauge builds stay constant. The difference was I used 30 gauge on my P2 and 28 gauge on my P3 so it's possible the Provari itself was reading it inconsistently and the build itself was constant.
And yes, I will realize some resistance fluctuations too. Not so much with 28 gauge but definitely with 30 gauge. Never could figure that out. Sometimes it would fluctuate up and then return to the original level. Sometimes it would gradually increase over time. My 28 gauge builds stay constant. The difference was I used 30 gauge on my P2 and 28 gauge on my P3 so it's possible the Provari itself was reading it inconsistently and the build itself was constant.