Stop in for a cup of coffee

95 mustang,5.0. Out of the blue it starts funning hotter than normal,02s reads lean and detonation when accellerating. Timing bang on. Oxygen sensors are active and within operating range. I asked where last fueled up, exactly as expected. Local co-op. Notorious for too much ethanol.
Waste of a morning. Cant charge for a non-repair.
Hey service call ...lol When my furnace went down they wanted $100.00 for a service call.