Let's not get to technical here. If I had to guess with out seeing it I would say a fuel issue after setting all winter. IE: condensation in the tank= check water separator if installed & run it low on fuel before you put fresh fuel in it. Reverse could very possibly be a sticky lower shift cable, put some time on it and see if it still does it. If not it will have to be addressed. If I can help you out feel free to contact me.