Already checked all the threads on TGO regarding this topic using the search tool and did the following but still the 89 RS 2.8 liter is wanting to stall under load:

Checked for Intake Blockage, clear
Checked for Vacuum Leaks, none found
Cleaned Throttle Body, wasn't very dirty but cleaned it anyways
Checked Fuel Pressure
Checked Fuel Injectors for correct resistance per TGO; replaced 3 of them
Cleaned Fuel Lines by adding Seafoam to the tank,car has been sitting a while
Fuel Filter was recently changed
Checked Throttle Position Sensor per TGO, good
Checked Spark Plugs and Wires, all good
Replaced O2 Sensor
Checked and Cleaned IAD (has 4 electrical connectors with little diaphragm)
Replaced temp sensors
Reset Timing
Reset Computer

After all that, the car runs a little better, but still not like it should. It will drop to around 400 RPMs when taking off from and light and you have to go to WOT to get it going and it struggles past 35mph.

Any suggestions to fixing this problem are appreciated.

TJ

 

It was better on the drive home, but not by much. Couldn't go over 40mph up even the mildest of grades and couldn't rev past 3500rpms. Turbo_Jimi forgot to mention a few things: Its not throwing any codes and the three injectors we replaced tested good (for resistance) after we pulled them. It also idles rough and feels like it wants to die when stopped. We gutted the cat a few years ago also.

 

One thing we did not do was check for compression.