Does over full oil on dipstick cause engine light and rough idle when start cold on 2000 Chevrolet Silverado 1500

just bought truck, enigne light came on after driveing a couple days guy put full synthetic in the truck recently and now it idles a little rough when i start it and oil is over full by a little bit on dipstick all power seems there not sure temp guage runs colder then normal as well guy said he put something in the truck to make it do that but ive never heard of a truck running colder.

Asked by for the 2000 Chevrolet Silverado 1500
over full oil can cause issues depending on how over full it is. the trk should run at 210 degrees unless thermostat is removed. it needs to run that hot for components to work properly
thank you for your help that engine light just now turned off i dont know whats up with it im going to drain some oil, the temp guage seems to be all over the place but wont pass 210 degres do you know what may be causeing this to read this way?
read the codes and 210 is normal for this trk
what would cause the truck to run cold it doesnt get hot for some time. the thermo stat jumps all over the place under 210 never stays there.
what would suggest in me doing to start to fix this problem. i found some stuff on the web just not sure where to go with it. thank you agian for helping me out.