99 Gt runability issue

[bowtie387]

I bought this car from my wifes uncle. It needed a upper intake manifold so I fixed it and put new Delco wires and plugs in and changed the oil. Car has 82000 and cleaned up very nice. Ok now for the problem. After driving for 15 minutes plus you will pull up to a stoplight and take off and it is at a big loss for power. Pull up to the next stoplight and it will run fine. Since this I have also put a new cat on. I cannot figure this thing out and it does not have any codes or ses light on. Any ideas would be greatly aprreciated. Thanks

[02BlueGT]

Check fuel pressure....


Try the Maf (drive the car with it unplugged)


Also Check for vacuum leaks, they can cause various problems

[bowtie387]

I will check it out today. Thanks for the reply.

[bowtie387]

Well after digging farther I have found the problem bu dont know whats causing it. When it loses power timing will drop to 0 sometimes -3 from 20degrees. I can stop and take off and sometimes it runs great with full timing, then the next time the timing will retard and have a big loss of power. Any ideas would be appreciated. I have put new acdelco plugs and wires on, maf, icm,and cat in the process of this. Also was told to disconnect o2 sensor and drive it to see if that changed anything with no success. Thanks

[UR LOSN]

are you able to scan for knock?

[bowtie387]

No only ablr to watch timing

[bowtie387]

I was able to watch live data on a solus, And its showing 15* of Kr. But 6 out of 10 times it has 0 to 4 and runs fine. Im stumped any ideas?

[bowtie387]

Drove it again and it ran great for 20 to 30 min. Then started acting up a few times. Anybody have any ideas?

[bowtie387]

Nobody has any ideas?