Idles rough, lose power when reaching operating temp

Hello everyone

I have a 1994 Silverado K1500, 120 K miles, V6 4.3L engine, manual trans, throtle body, new sparks, wires, cap distr, new air filter, just donw the oil change, pretty new exaust pipes, new O2 sensor, timing at 5 deg BTDC. When I start the car the idle speed jumps between 300-900 rpm, but the car still has somewhat power. As I start driving it, the car has power but the tach is still jumpy. When the car reaches operating temp at 195 deg the car loses power, I can hear a constant pop sound in the exaust and when I punch the gas the tach needle will not come down right away, it feels like it gets stuck.

If anyone has any suggestions on this, could it be some of the sensors conected with the emissions?
Thanks a lot everyone, Raz

This sounds like a clogged cat to me. Is it the original cat? Do you even have a cat?

Drive it at night and park in a dark area and see if the cat is glowing red. An exhaust back pressure gauge can also be hooked up to see if there is a restriction in the exhaust.

//2000CAYukon

when you set timing did you disconect the computer controle to the distributer? the exaust can glow red if you have to much unburned fuel in the exaust. make sure you disconect the computer cotrole from the distributer and set timing.

Thanks guys, I'm a little late with the reply, will test for the cat tonight see if it glows red, yes, it is the original cat and also yes, I did disconect the conector for the timing and then reconected before I started the car again. Thank you once again for the help will let you know what I find about the cat.