89 suburban cuts out/ blinking engine light

[no idea]

Hello all looking for some help, got an 89 2500R 5.7 2 wheel drive Suburban ran good the person who owned it before me got it tuned up changed the heater core and a couple of other things. Put plates on the truck went to dinner with the wife and kids came out wouldn't start. Had it towed home.

Replaced the fuel pump,fuel filter, cleaned the gas tank, changed the pig tail connection for the fuel pump, rebuilt the throttle body, changed both sets of wires for the injectors, changed the coolant tempture sensor,then changed the ECM using the same prom and calpak, followed all directions diconnected the battery changed it out reconnected the battery truck started right up. BEUTIFUL. got a code 12 ( nothing wrong) drove around got gas a sticker, truck running a little slugish I would step on the gas and it wouldn't really go then it just took off, after about 30 or 40 miles of driving the truck cut out back to same problem. now truck will start but cuts out after a few minutes even if it is at idel or if I am giving it gas. also the check engine light blinks a steady and constant blink, any help would be greattly appercated. I am a wood refinisher by trade so I really don't know all of the tech terms that you all use unless it is in my repair book.

[dougbfresh]

Pull the codes and check the fuel pressure again.

[Saltmine]

Might have the wrong gas cap, too. We had a GM pickup in the fleet that would run fine around town, but on the highway it would get sluggish, and eventually quit. If you let it sit for a while, it would restart and run fine. I was called out on a road call for it once, and when I got to the truck, I decided to check to see if the fuel pump was running, by listening at the filler. When I opened the cap, a great whoosh came out.
The vent lines were pinched on the tank, and the non-vented cap wasn't allowing the vacuum to disipate in the tank as fuel was used up. Eventually, the vacuum became greater than the fuel pump could overcome, and it would starve out.
I got it back to the shop, with the cap loose, and put it on a lift. After re-routing the vent lines on the fuel tank and changing the gas cap, the truck never had another problem.

[no idea]

Thank you both for your in sight I will try both soultions and let you know