My 89 gtu lacks any power under load. It is drivable and performs ok under light load but as soon as I depress the gas more than 1/3 of the way it sputters and coughs and has to accelleration. I've replaced the air and fuel filters, spark plugs, fuel pump, reset the ignition timing, and checked the tps. Its not clogged cats as i have straight pipes nor is it the 5th/6th ports (happens below 3800 to). Before my fuel system pressure was low but now its within specs, although there was no improvement. Any Help?

 

First, if you haven't checked the engine compression, you should do that before you do anything else. Low compression in one or both chambers=low power output.

If compression is good, and considering everything you have done so far, the "sputters and coughs" symptom could indicate fouled injectors. May want to have them professionally cleaned and tested (~$50 USD).

 

I don't really have time to send off the injectors as this car is my daily driver, but i ran a bottle of cleaner through with no luck. It smells like its running rich (which could be the lack of cats) and the way i get afterburn when its under load i think its getting enough fuel. I was thinking that maybe my spark wasnt hot enough for the additional fuel that it receives under load.

 

How are your grounds, I had similar problems when I first bought my TII and they went away as soon as I redid my grounds.