Jeep wont start,recently had in shop, they replaced a switch on gear stick,said it was not engaging.maybe 3 months ago. i have new battery & wire terminals,new plugs wires and distributor with new rotor button. Well jeep has run fine except still struggling to crank.....yesterday it won't crank but is turning over.....just like it did when shop replaced switch but even then it still struggled to crank. What would you suggest ???