My wife's 60" mower [ she doesn't let me use it] has lost power when engaging the blades and or trying to climb a hill. Previously she had no problem and the mower was faster than she needed. now it is a slug. I have changed the plugs, thought the carb may have a problem because of the crappy gas but it was free of any debris but I tore it down and soaked it for 4 hours in new cleaner. Replaced the fuel pump the filter and all fuel lines, still no progress. Ran a compression test and had 100 and 105 psi, I now suspect an ignition problem, can anyone help me out ? Appreciate your response.