This all started with plugged fuel injectors (I think.) Coming home the truck ran terrible with no power. (When cruising at speed on freeway I tried to accelerate but the truck ran rough, and the condition got worse off the freeway; the truck would not accelerate up hill - I had to take an easy hill at 35mph.) Then the truck would not start the next morning. The injectors were plugged, but I fixed that and the fuel pump is fine, and the truck still would not start. Here is what I have done since: New EGR valve, new vacuum lines, new intake manifold gaskets, upper and lower, new throttle body gasket (old one was sucked part way into manifold), new air bypass valve, new plugs, new wires, new cap and rotor, new TFI module. The truck has spark and fuel, and now when I get it started and on the road it runs better than it has for a long time. However the idle is rough and surging and the truck will not start cold. When idling the vacuum is about 17.5 in hg but there is no vacuum when I crank it over to start. I went back and retorqued the manifold gasket bolts and plugged up every vacuum line but still no vacuum when cranking. I start the truck by unplugging the air bypass valve and have my brother turn the key to start it, and I immediately plug the valve back in once the truck catches. We used the Chiltons manual and tested the air charge temperatur sensor and the engine coolant temperature sensor, and they were within range. We bought a new throttle position sensor, but it tested identical to our old one with an ohmmeter, so we returned it. We do not know what to do. It seems like the computer is opening the idle bypass too much when I try to start. The truck always did idle too fast, but it idled smooth and never had any problem starting. The engine running self test has a code 13 which my book says means the idle is wrong and to check vacuum hoses, throttle plates/linkage and idle speed control. Does anyone have an idea about what is wrong?