Toyota Platz (Echo) problems, NEED HELP!!!!!

Hello there everyone. I am writing here today to get some consumer reviews about the car Toyota Platz (or Echo).
Well our car is a 2004 Toyota Platz. It usually comes with an 1 liter 2NZ-FE engine. But we changed it to an 1.5 liter 1NZ-FE engine before we imported it. We’ve owned this car since 2008. In its early days with us, it didn’t show that many problem expect for only 2 things: its small radiator got burnt and so we replaced it with Toyota G Corolla’s radiator. And the other problem was that its engine mountains got damaged. Well in the recent times ( for last 2 months) its showing a lot of symptoms like the electrical circuit became a direct line, the radiator becoming overheat though there is plenty of coolent left and the radiator fan is on, the gear gets loosed above 60kph, the ABS doesn’t get activated.
I just want to know is there any Platz or Echo owner in this community with such problems?
Thanks in advance.