A very common problem is inadequate cleaning of the connector pins where the chip plugs in. Not the chips pins, the ECU board in your PCM where it plugs in.
They are covered with "solder mask" material from the factory and if you don't clean them JUST RIGHT, you get intermittent contact and all sorts of things can happen.
First step is to revisit the install and try doing the connector cleaning again. That's where I'd start if I were in that situation, based on everything I've read over the years with people having these problems.
By the way: cleaning that right is really difficult sometimes and it's not a reflection on you if it didn't go perfectly -- MANY have experienced this.