Things to check:
Spark plug
Air filter
Carburetor settings
It could have an engine problem
Your 1987 Astro might go full throttle when the engine is started because the throttle is sticking. This could also be a problem with the starter or the ignition hanging during the start.
At full throttle (when you put your foot down all the way on the gas), the engine will struggle to work and might appear sluggish when moving from a stop.
The throttle position sensor, TPS, tells the engine control module,ECM where the throttle blade is. It is the primary way that the ECM knows what you want out of the engine. There is a backup system if the TPS fails, but it is not as efficient as the TPS. So what does happen. The engine will not be as responsive to the throttle as it should be. When you accelerate there may be a pause while the ECM realizes what you did. If you let off the of the accelerator the engine may take a few moments to return to idle or may idle rough and have a minor surge. It will ultimately return to idle. The engine will still run, but will be sluggish and lose its pep.
Toyota's need to be serviced often.. otherwise they tend to turn their engine oil into sludge. this may be your problem.
Throttle plate stuck Control cable bound? Throttle body assembly?
A bad throttle sensor can cause engine jerking and rough running. A test of the computer codes should show if there seems to be a problem with the sensor.
It would depend on what the problem is. All throttle problems can lead to a non running engine.
I had same problem with my 98. Mine was the throttle body area. What happens is the throttle body gets carboned up and makes the accellerator sticky and causes the hesitation... To fix: 1. remove the large rubber intake from throttle body. 2. start engine. 3. spray throttle body cleaner (large amount) inside butterfly area of throttle body as you rev the engine to keep it running. 4. done.
there is a throttle position sensor on the firewall side of the throttle body. unplug it, and see if the engine runs the same. if it runs the same then, yes you do have a bad throttle body, and if it does not run the same, i would suggest having the engine looked at to figure out what the problem is
it might be your throttle
I had the same problem and it is your oxygen sensor.