winning a won game

My personal nemesis is "winning a won game", opponents at the club I used to go to noticed I play better down a piece. Is this common?

I don't have much accuracy I guess, just a tough fighting Scotch-Irish spirit, rout for the underdog and don't resign early.

It's harder to win a lost game.

I blow a lot of openings, but just keep getting stronger as the game goes on, have a strong endgame...often at the beginning, I see many good possibilities but have trouble discerning the best move.

I'd recommend playing so training games (slow/rapid) against lower rated players, weaker opposition. This helps you practice your technique. 

If you want, we can also play some training games where I give you some kind of odds in the opening (manually), and you have to try and win. I love playing a piece down!

 I get beat against a lot of lower rated opponents....then give good games or win against higher rated ones, go figure....not very consistent...but capable of playing a good game on occasion....okay, challenge me...love to play higher rated, don't really care much if I lose, you don't have to give odds unless that floats your boat...been through the humbling experiences in life many times.

It's often not easy to win a won game, but at other times it makes it easier to find the right move.  My moves from the following position, based on chess.com's CAPS and Lucas Chess's analysis algorithms, were WAY better than normal for me. I got inefficient in the endgame, but I played it safe and kept the edge:  The "Hold The Advantage" drill here at chess.com is a good way of playing against a very strong computer opponent (Computer Level 10 = ELO 2200, supposedly) with a chance of hanging on.

Here's the nice position the drill starting me with:

The chess com move analysis:

Lucas Chess/Stockfish 8 Move Analysis has given me slightly higher scores in other games, but most of the moves it didn't like here were in the endgame, which I played safe but not very efficiently:

wow, thanks, that's interesting, never used CAPS, not sure if statistical chess is my style because I can't afford to pay for it....I just wing it...lol.

It says you only accept with rating lower than 1890 or something. You can just make a 3 day unrated challenge to me if you want - my settings are for all ratings. 

Thanks Cherub, I did not know how it was set...did that a long time ago....I reset it to accept challenges....rated or unrated doesn't matter to me...

I think its important to realise that thinking we have  a 'won' board position is misleading and lulls us into a false sense of security. If it were a truly 'won' position, the finish would be easy and we would win the game. Therefore I think we have to view a good board position as being 'better' and no more.

This leads me to my next point - if we accept we are just 'better' - then this keeps us grounded and looking for some knockout blow maybe incorrect strategy and the position might not be good enough to warrant that anyway.

Sometimes, you just need to control the position and improve it as much as possible, kill opponents counterplay, keep increasing the pressure,  be patient and wait for your moment. Sometimes, your win will be a direct attack, sometimes the win is to be found trading material and going for a superior endgame, sometimes your opponent will simply crack under the strain.

Above everything else, do not commit suicide and hand your opponent a win they do not deserve.

I like the way Kummer teaches...very entertaining...chess can be dull or exciting, and he makes it exciting.