I got a 90 silverado 1500 350 4x4 auto. 160000 miles. has new plugs, wires, cap and rotor. everytime you start it it acts like it wants to stall. like not getting enough gas or spark. then after about half a minute of running it idles fine. it doesn't matter if the motor is hot or cold it does it everytime. and it only gets 10 mpg. its a stock truck with stock tires. shouldn't get like 15 mpg or close to it.