I have a 1998 ford explorer. Had codes read, needed a new Mass air flow sensor. Got a used one off ebay. Check engine light came back on. So I disconnected plug to MAFS. Then when i drove it, had to baby it to get it moving,but ran good at normal speeds, but when I slowed down and tramission down shifted, it would down shift hard. So when I got home ,I jumpered the wires by putting 2 wires in the plug. It started and ran for about 10 sec and then cut off. I tried to start again and all it would do is turn over but wouldnt start. I removed jumper wires and disconnected battery hoping this would clear computer, it will turn over but wont start, any suggestion besides quit screwing with it and take to shop.