My 1988 k1500 stepside is not running well

[MEG3r]

At the moment i am working on my k1500 5.7 tbi and it’s been on and off recently. The truck struggles to speed up past 10-20 mph sometimes, other times the truck runs fine, if I stop the truck and turn it off and on it sometimes works, but can still hear the rpm going crazy and feels like it’s not catching a gear and when it does it jumps a little. Anyone have any tips ? I’m desperate

Fixed the spark plugs and wires
New 02 sensor

 

[Caman96]

When was last fuel filter changed? Check all your grounds?

 

[Sean Buick 76]

Sounds like a smoked transmission

 

[Schurkey]

As said--is this an engine problem, a transmission problem...or both?

What is the fuel pressure at prime, and when running?
How old is the fuel filter?
How old are the distributor cap, rotor, plug wires, PCV valve? Has the ignition timing been verified--initial plus electronic advance?
Does the EGR work properly--shut off at idle?

Any chance the catalytic converter is plugged? Exhaust pipes crushed/restricted?

Connect a scan tool, find out what the computer wants you to know. Fuel trims, plus coolant temp sensor, throttle position sensor, and MAP sensor would be my initial focus, but verify EVERY sensor and computer output.

Does the truck drive better in Reverse? Does it idle and rev OK in neutral/Park?

 

[MEG3r]

As said--is this an engine problem, a transmission problem...or both?

What is the fuel pressure at prime, and when running?
How old is the fuel filter?
How old are the distributor cap, rotor, plug wires, PCV valve? Has the ignition timing been verified--initial plus electronic advance?
Does the EGR work properly--shut off at idle?

Any chance the catalytic converter is plugged? Exhaust pipes crushed/restricted?

Connect a scan tool, find out what the computer wants you to know. Fuel trims, plus coolant temp sensor, throttle position sensor, and MAP sensor would be my initial focus, but verify EVERY sensor and computer output.

Does the truck drive better in Reverse? Does it idle and rev OK in neutral/Park?

It revs really bad and stutters almost. The truck will even shake a little bit. I just replaced the IAC Valve exhaust pipes and catty are fine. It’s throwing code 13

 

[MEG3r]

And now it’s throwing up both codes 13 and 44

 

[MEG3r]

As said--is this an engine problem, a transmission problem...or both?

What is the fuel pressure at prime, and when running?
How old is the fuel filter?
How old are the distributor cap, rotor, plug wires, PCV valve? Has the ignition timing been verified--initial plus electronic advance?
Does the EGR work properly--shut off at idle?

Any chance the catalytic converter is plugged? Exhaust pipes crushed/restricted?

Connect a scan tool, find out what the computer wants you to know. Fuel trims, plus coolant temp sensor, throttle position sensor, and MAP sensor would be my initial focus, but verify EVERY sensor and computer output.

Does the truck drive better in Reverse? Does it idle and rev OK in neutral/Park?

Fuel filter was new when I bought the truck 4 months ago. And I’ve driven it not even 1000 miles new plug wires when I replaced the plugs themselves. I’m taking it to a mechanic on Monday but please let me know anything you can, the fuel pressure will go a little over 30

 

[Schurkey]

Download the service manual set for your vehicle from the links in the Sticky thread section of the Engine forum.

Follow the diagnostic procedure for codes 13 and 44.

the fuel pressure will go a little over 30

That's totally unreasonable. Nearly 3 times the stock fuel pressure--unless you're restricting the return plumbing which tests fuel pump ultimate pressure but isn't really helpful for determining the running pressure.