Speed My 1990 Trooper does fine on flat roads but whenever the slightest incline comes, I have to apply so much gas to try to keep up. It takes some time to swich gears to pick up speed. Would a major tune up do the trick?

If you apply a separate ground (one side is 12 volts one is grounded by the cars computer) to the idle speed control valve does the engine race up in RPM

Check that ALL vacuum lines are connected, and properly.

time for a tune up -new plugs,cap and rotor,fuel filter,air filter,fuel injector cleaner-goes in the gas tank-cheers Denny

How's your fuel filter ?

going down steep hills will all but over ride a cruise control, since the motor is trying to keep the vehicle slowed to what your desired speed that you set , unfortunately this doesn't always work,, as your speed increases, the motor can't keep the speed reduced, when you apply the brakes, the system shuts off, cruise controls were meant to be used pretty much on long flat surfaces with Low inclines ,,

check the timing cuoldbe wrong

when you turn the switch on listen in the fuel tank to see if the fuel pump comes on

With all you've done so far I'd have to say that I'd be tempted to take it to a good tranny shop just for sake of a diagnosis, which the mechanic can probably do free of charge, and a little drive down the road. Almost sounds like it's trying to take off in second gear or something. Other than that, the only thing that comes to mind at all is possible plugged exhaust, like catalytic converter.

Well, could be many things, but first and easiest, check the dist. cap and rotor, and all the plug connections. Any moisture will freeze and short out the ignition system. Also change the fuel filter. If you get the slightest moisture in the fuel it will lock up the filter when the water freezes. Could be a relay, probably "engine relay" that sticks when it gets too cold.

Some starting points I hope.

Look under the plastic intake tube for a hole