1990 Mighty Max Keeps Shutting off

I am new to the forum and I decided to post this question here.

Last summer I decided to start working on a mighty max that has been sitting for around 10 years. I replaced the fuel pump the ECU the mass air flow sensor, I even put a new gas tank on it. When ever you drive it, at a certain speed the truck will shut off and you will have to restart it. It usually happens in third gear. It could be that the new ECU is bad, or the new Mass airflow sensor is bad.

I just cannot seem to figure out what is wrong with it. I plan to work on it some more this summer, but any suggestions would help. The Mighty Max that is my profile picture is the mighty max that I am working on.

One more thing, any suggestions on parts will be welcome, as there are a few good junkyards about 15 minutes away.

One item you might check is the fuel filter. It's one of those things you don't think about much, but if you don't check it, you don't know if it's ever been replaced. The fuel filter in my truck likely had never been replaced until I took the time to do so. Curious, I cut the old one open, and was stunned at the rust and filth it had inside. For a truck that has been sitting for 10 years, that stuff is probably worse.

The filter is under the driver's side door, on the inner frame. If yours' is fuel injected, you'll need to unbolt it. If it's been on there a long time, it will need some bolt-loosener (PB Blaster, Liquid Wrench) just to get it off. The replacement filters aren't cheap...around $20...but they do make a difference in performance, and keeping Jimmy Hoffa Particulate out of your fuel system. A clogged filter will allow the engine to idle okay, but when the demand for more fuel at higher speeds comes up, the fuel pump is trying to push fuel through all that gunk.
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By your indications you have a 2.4, but it's helpful for you and the forum if you can positively identify the type engine you have. Look at the metal tag on the truck's firewall to identify the engine.

I found that Advanced Auto parts is very limited in the replacement parts they offer for these trucks, and usually they'll have to be ordered. NAPA is a bit better, but my personal experience with a NAPA veteran parts-man is that they can't compete with RockAuto.com for price, parts and availability. RockAuto also uses several different shipping companies instead of just UPS, so you'll get your parts in a very timely manner.

Stop in to our auto manuals section if you need printed mechanic information also. Troubleshooting sections are always included in a manual and you can download it and view it at your convenience.

the TPS might cause the problem too
I would crack open ECU and see if you have bad Caps