When driving at seventy mph hour the engine will drop down to forty five mph on its own

Hi and thanks for using 2CarPros.com.

Based on your description, it could be many things. If the check engine light has come on, I recommend having the computer scanned to determine what codes are stored. Here is a video showing how to use a scanner:

https://youtu.be/YV3TRZwer8k

If you do not have access to a scanner, most parts stores will check them for free.

If no trouble codes are found, I would then recommend checking the fuel pump pressure. Low fuel pressure can cause the engine to lose power and slow down, especially on hills and higher speeds. Here is a link which discusses checking fuel pump pressure as well as the pressure regulator. You will need a gauge, but most parts stores will lend you one.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

If you determine the pump is an issue, here are general directions for replacement:

https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump

I have attached a picture listing the fuel pressures for 1994 vehicles. Yours is the last one (others).

If fuel pressure is not the issue, check to make sure there is no a problem with the catalytic converter plugging. Here is a link discussing the symptoms:

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

Here is a link which discusses how to check the converter:

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

I hope you find this helpful. Let me know what you find or if you have other questions.

Take care,
Joe

One simple check is to remove the air filter housing and look at the mass airflow sensor element. Have had many of these contaminated with dirt or bugs, this will adversely affect fuel delivery and speed of the vehicle. I used to get those all the time. Your local parts store should have mass airflow cleaner spray. This is only if it is contaminated.