Please help! 1990 gmc 1500 (5.0, 305) stumbles, hesitates when col

[Wizey04]

Hi everyone.

I have a 1990 gmc half ton with the 305.

Every time I start it when it's cold it wants to hesitate and stumble upon low rpms.

For example: if I start it when it's cold, put it in gear, hold down on the brake, and slightly hit the gas it wants to die out.

It also shifts hard from first to second when cold.

Once the engine warms up all of the symptoms seem to go away.

Also cranks for a couple seconds before starting.

Truck is also giving code 44 (running lean)

List of parts I've change:

 

-fuel pump and sending unit

-fuel filter

-02 sensor

-air filter

-plugs

-wires

-cap and rotor

-egr valve

-egr solenoid

-cts tested good

-injectors look to be spraying good

-checked all vacuum lines

-swapped a map sensor from my buddies truck to see if it changed and didn't

-cleaned IAC

 

Sick of throwing money at this and having no positive results.

Any help would be much appreciated.

Like to get some opinions.

Fuel pressure regulator?

TPS?

[Dnt]

Go with an aftermarket CAI your plastic intake runner has a imperceptible crack in it.

[O_J_Simpson]

Gasket under your TBI?

[Wizey04]

I sprayed around with starting fluid and didn't notice a change in idle.

[rjgti]

measure your temp sensor

[Wizey04]

Yes, I metered my temp sensor.

[rjgti]

check fuel pressure

[rjgti]

I believe tps should be set to about .7 v with koeo

[Wizey04]

I did check the fuel pressure.

It was around 6-7 psi.

Changed out the pump, got her back up to 12 psi.

Noticed a difference on throttle response at higher rpm's, but the cold start problem is still there.

That's why Im thinking it's the fuel pressure regulator on the tbi.

When fuel was tested it was tested before it reached the regulator.

[Wizey04]

Gonna throw a throttle body rebuild kit on tonight.

It comes with the diaphragm for the regulator also, so I'll keep posted.

[rjgti]

if you pinch the return fuel line you should of seen pressure increase if it is a bad reg

[Wizey04]

Well I pulled off and disassembled my throttle body.

Pulled apart my pressure regulator and the spring was broke into 4 pieces!!!!

Good deal.

I'll let y'all know how she runs.

[rjgti]

sweet, nice find

[Wizey04]

Runs like a champ!

Again it was the spring for the fuel pressure regulator.

I appreciate everyone's input and hope that if someone has the same issues as I, they come across this forum.

Thanks again.