Sputters underload only
 

All of a sudden she, a 1987 n/a started sputtering (would not accurate/ cutout) past 3.5kish at the end of my hour commute, free rev was normal everything was normal besides the sputtering. Parked it for 2 hours and drove back home fine. Checked the car, cleaned the plugs, got new gas. The next couple of days she drove normal to work and back 20 minutes each way. Then, today it happened again during a brutal 2 hour commute, way worst this time. All of a sudden couldn't drive above 80 mph on my way back! Parked the car for 15 minutes ran fine after words. If I stay under 3.5ish everything seems normal. If I take a 20 minute or less trip everything is fine.

I could redo every ground, pressure test, tps, ecu resolder, new lead coil and the list goes on. What would likely be the problem being it is intermitting on longer trips? Thank you, Rotary Friends!

Check fuel filters, especially the sock in the tank.