Hopefully someone knows about GM 3.1s

[Vanquish502]

My cousins car decided to have an attitude change one night after he tried going home after work.

All day long it ran great. He got to an intersection by work and it stalled? It started back up and he drove it to work fine.

After work he got in and started it up and it idles fine....but it wont go past 3000 RPM(give or take a few)

It almost seems like a gas problem. The fuel lines were replaced today and it still seems like its choking. The pressure in the fuel rails is 37 PSI, where it should be. Why the hell is it doing this?

Put the pedal to the floor and the RPM climbs quickly to around 3000RPM but then drops slowly as if theres a miss, which there isnt.

I've been told to check things like the TPS, and the crank position sensor.

Could these be the problem?

BTW its a 1989 Oldsmobile Cutlass Supreme Intl. with the 3.1L V6.

 

[falls chic]

Yeah it could be all those things,also check your MAP sensor, make sure there is a good vaccum connection to it. It could also be the fuel pressure regulator,or vaccum to it(FPR).Those things are pretty hard to diagnose.If all those things are ok you might have to check the module or computer. We had an '88 cavalier w/ a2.8ltr. Glad to see it go!! Sold it when we bought our EX. Oh yeah find your diagnostic connector, probably under the dash. Use a jumper wire from terminal Ato B(looking at rectangle 12th pin diagnostic terminalA&B terminals are top 2 right terminals on clip side of rectangle). It should be marked,turn the key to the run position,the check engine code it should flash 1,2. Meaning it should flash once pause and then flash twice. The code will repeat itself 2 more times.If additional codes have been stored they will follow code 12. Again each trouble code will flash 3 times before moving on. If you can tell me what codes come up, i can tell you what they are. Good luck! If you have any more ? let me know and i will try and help.