Doesn't want to idle runs very rough and rich at high rpms and the reverse light flashes off and on. I put a new speed sensor and carb kit in didn't help. pickup coil and stator tested within specs

Was the fuel drained out and flushed ? The engine coolant temperature sensor may be bad and reading too low causing an overly rich mixture .

How long since a tune-up? Have you checked the timing? How many miles on engine? How is your cylinder compression?
There isn't much load on engine in park or neutral. When you put it in gear, there is a load on the engine. With carbed engine 6--8 psi fuel pressure. Crub idle in drive, 575 rpms. With a high mileage engine, that idle speed may not work. Is there an idle screw on the carb, where you can up the idle to keep it from stalling, in gear? Of course if you do that, when you put it in park or neutral the idle is going to go high, I know it's a pain. If your engine is in poor shape, your probably going to have a tough time, getting it to run correctly. Just my opinion.

Car idle is rough Inspection Service & Cost A rough idling engine can be caused by a number of issues, some of them are serious while others tend to be minor, but the symptoms remain pretty much the same. The car will feel rough and bouncy when the engine is running. The car will also idle below its regular speed, display inconsistent RPMs and may produce a shaking, skipping or slipping sound when the vehicle is running.
While a rough idling engine may seem to be a simple inconvenience it often indicates a deeper problem within the engine. The vehicle should be inspected and repaired as soon as possible because small problems have a way of turning into expensive repairs. How this system works: The idle speed of an engine is basically the rotational speed the engine runs on when it is un-coupled from the drivetrain and the throttle pedal is not being depressed. The idle speed is measured in the revolutions per minute of the crankshaft.
When an engine is running at idle speed it generates enough power to smoothly operate equipment such as the water pump, alternator, and power steering but not enough power to move the vehicle itself. A passenger car will usually idle between 600 RPMs and 1000 RPMs. A properly functioning idle should run smoothly without skipping or slipping. Common reasons for this to happen:

• Dirty Fuel Injectors: The fuel injection system injects fuel into the cylinders, which creates a mix of air, and fuel to ignite and burn. Fuel injectors have tiny nozzles to spray the fuel into the cylinder and they can become clogged over time. clogged or failing fuel injector creates a lack of fuel in the vehicle's engine. This can cause a rough idle, it can also cause symptoms such as slow acceleration or the car not feeling as if it has enough power. If the problem is addressed early, it is possible to clean the injectors, which will restore them to full function. If this condition is not addressed in a timely manner the injectors will need to be replaced. Incorrect Idle Speed: While the average idle speed falls between 600 to 1,000 RPMs, if your vehicle is experiencing a rough idle it could be due to an incorrect idle speed setting. A trained mechanic can easily adjust the idle speed, and it should stay at the proper speed. If an adjusted idle speed becomes inconsistent or changes at random intervals there may be a bigger problem that needs to be explored. Vacuum Leak: If the vacuum system has a leak, it can seriously affect the ability of the vehicle's computer to regulate the air to fuel ratio. This can lead to a rough idle and if the problem is not addressed the car may experience slow acceleration and a lack of power. Vacuum leaks should be inspected and repaired immediately. Incorrectly Installed or Damaged Plugs: Spark plugs are responsible for creating the spark that allows the vehicle to burn fuel. If spark plugs are improperly installed or malfunctioning, the idle speed can be affected. The vehicle's engine may vibrate or there may be slipping or straining sounds coming from the engine. Defective or Clogged Fuel Pump: A rough idle can be related to fuel delivery issues. The fuel pump, which is responsible for pulling fuel from the gas tank to the fuel injectors, can become clogged or defective. If this happens the engine will not get enough fuel, which can cause a rough idle, sputtering, stalling and even slow acceleration. Clogged Fuel Filter: A clogged fuel filter can cause similar problems. The job of the fuel filter is to screen out contaminants in the fuel, over time it will become clogged and need to be replaced. A rough idle is one symptom of a clogged fuel filter. Failing Electrical Components: A problem or failure in the ignition system or various electronic components can cause a rough idle. If this is the case, the problem will usually get worse as RPMs increase. Common culprits include the ignition control module, plug wires, coils, and spark plugs. Defective Airflow Sensor: A defective airflow sensor can be responsible for a rough idle. A mass airflow sensor detects the amount of air coming into the fuel injection system and sends that information to the vehicle's computer. The computer uses that data to deliver the proper amount of fuel to the air in the vehicle. Over time these sensors can malfunction or become dirty. One of the first symptoms of a malfunctioning airflow sensor is a rough idle. The car may also accelerate slowly and even stutter or stall as the problem progresses. Dirty Oxygen Sensor: Oxygen sensors measure how rich or lean the gases are as they exit the combustion chamber. Depending on the results, the amount of fuel entering the engine is adjusted by the vehicle computer. The ultimate goal is to maintain an ideal mixture that produces the lowest emissions. A dirty or failing oxygen sensor will usually trigger the check engine light and can lead to a rough idle, lower fuel efficiency and failed emission test.

check for vacuum leaks,the throttle position sensor and the map sensor to see if they are working correctly.

If the idle speed is normal until you shift into a gear, the idle air control valve is probably raising the idle speed. Try unplugging the iac motor at idle then shift into drive.
If the IAC is raising the RPM the computer controls it, so for some reason the computer thinks the RPM needs to go up. I am assuming you do not have a check engine light on or you would have checked for trouble codes.
Just for the record, I am showing the same IAC for both transmissions on a 2.0 engine code 3.
Is it possible the battery was disconnected and the learn process needs to be done for the computer to know where normal idle speed is ?

o-2 sensor

no, you have to know what the codes are. something told the o2 sensor to acknowledge that trk was running lean, rich, has misfires ? out on the limb, I'm going to say spray around the intake gasket (when truck is running ) where it meets the heads and block with carb/choke cleaner and notice the rpms on motor. If it effects the rpm then you have a bad intake gasket which will cause stalling and rough idle.

have you thought about the idle air control (iac) or T.p.s sensor try unpluging the Iac see what happens. Just a thought also listen for a vacum leak

Check and clean the IAC valve. Idle Control Valve. Use brake cleaner or carburater cleaner . Remove the duct work from the air filter assembly. It is located just inside . Run the engine at 1200 rpms and spray the valve. The valve can also be removed and cleaned.