1988 DELTA 88 FUEL INJECTED BOGS WHEN TRY TO SPEED HIGHWAY

Could be the fuel filter. Watch the speed it happens. IE.. Ok at 50 MPH, hit 60 MPH it starts jerking. Clogged filers will give the pressure need, just not the volume of fuel need at higher speeds.

Probably too late but for other users searching: You probably have the 4T65 transmission like I did. This is the vehicle "hunting" in and out of overdrive on the highway (marked "D" on your dash) and you're probably on level (or close to) ground. You have two options: drive in the gear selection "3" (more fuel consumption though) or change your speed. I used to drop down to 53 MPH and it would stop, or on the highway @ 65 for it to go away.
Seems to be common in this trans around 60 MPH. Also - start saving for another vehicle or repair. This trans will start to slam into 2nd gear from a stop after it warms up (internal solenoid fix required) OR it will shudder horribly from a stop after a highway run. My fix was to replace the solenoid in the trans (there's video on YT) by pulling the right side of the drivetrain off the van and pulling the trans cover. If you go this route - you *must* ensure no -and I mean NO- dirt gets in that tranny while the cover is off.
Good luck!

could be faulty ignition module.f

fuel pump failing or stopped up fuel filter.

is there a rattle under the car like the cat converter is bad when was the fuel filter last replaced

High speed mis

If not ignition,I would suspect a vacuum leak

Have the intake smoked to check for leaks

Check all vacuum hoses,pcv,egr,etc

Fuel Filter and fuel pressure

Put a pressure gauge taped to the windshield
and drive 60 mph

mine does the same thing... check the relay behind the glovebox.

Hard to say on a older car such as this. If running well and healthly it should receive around 16 to 18 highway miles per gallon

could very well be a clogged cat converter

there are 2 or three fusible links in the main power cable i would check the ones from the starter

On this fine problem, you're looking at many possibilities. Only sure way, is to test things. Are you getting a SES (Service Engine Soon) light? If you do, start there, run the code and see what it is. If not, possible things could be, your spark plugs are old and cannot burn the fuel, you pretty much have a misfire, fuel injector(s) are dirty. Many things really. My car had that problem, and turned out I had a bent intake valve, so like I said, could be many things.