[jimberg]

Before advancing your timing, make sure that you have 92 octane in your tank. You check your timing by warming up the engine to operating temp, then you remove the SPOUT connector. The SPOUT connector is a jumper that is on one of the wires that plugs into the TFI module which is mounted on the side of the distributor. Make sure it's set at 10. I wouldn't worry about advancing your timing until you get your other problem figured out.

When you floor it, is the hesitation immediate, or does it occur at a certain RPM? If it's immediate, I would definitely check the voltage between the green and black wires on your throttle position sensor. Use a digital voltmeter set so you can read a range of 0-6 volts or so. When the throttle is completely closed, you should read less than 1 volt. .85 to .95 should be good. If it's over, try loosening the screws on your TPS and see if you can turn it until it goes below 1 volt. If you can't do that, make sure it's installed correctly, or replace it. If you are getting below 1 volt, then move the throttle slowly and make sure the voltage smoothly increases beyond 4 volts. You want to make sure that there are no holes where the voltage suddenly drops. The computer uses the TPS to determine three states. Closed throttle (<1volt), part throttle ( >1v to <4.5v), and wide open throttle (>4.5v). If it doesn't detect these states properly, it may use the wrong amount of fuel or timing advance.

Does the starter crank when you have problems starting? If it does, you should probably check the PCV valve. It's tucked between the intake plenum and the firewall, so it's pretty hard to spot. It's pretty much plugs into the back and center of the lower intake manifold. There's also a filter that goes under it which can get gummed up. I would replace both the filter and the pcv valve. You need to pull the rubber grommet in order to pull the filter. The filter is pretty much like a coarse steel wool so to remove it, you just jam a needle nose pliers down there an pull it straight up. Be sure you have a replacement before you do this.

As far as vacuum leaks go, check the gasket between the upper and lower intake. When the engine is at idle, you can spray some carb/choke cleaner at suspect areas and see if it affects the idle.