My 2005 Nissan Altima engine light was going on n off. N sluggish. Twice it need ed water. Im trying to do this on a low budget. A sensor reading of PO 300 came out on the small hand held machine

p0300 is multiple cylinder misfire I had a code of p0304 and moved my coil from 4 to 2 and the code went to p0302 so that told me that the 1 coil was misfiring and the p0300 means random/multiple cylinder misfire if I were you I would change the coils it helped me big time and gave my altima more power if the coils are misfiring it would cause that problem but first thing to change that is cheaper is change all 4 plugs first then if that don't fix the problem its the coils hope that helped

and if it needed water its a good chance the head gasket is gone that's what happened to me so I changed the head gasket and plugs and coils and that fixed mine hope that gives you the info you needed