I have a 1991 lx and i swapped in a 2.3 turbo from a turbocoupe. Whenever I start to get the boost up it will start to pull and then bog down for a second and then pull again. It keeps alternating this pattern. I have the throttle body from 91 on the turbo motor, I'm not sure if this would be causing the problem or not. I am also running the computer from an 88 turbocoupe but I have an 86 block and t3/t4 turbo. Any suggestions of what the problem could be??
I am running 89 octane, my timing is at 10 btdc. I just have the stock computer for an 1988 Thunderbird, I think its the LA2. I had to buy replacement injectors because the ones that were in the motor were shot and I just bought ones from Advance Auto Parts for an 86 turbocoupe.
I know I have the right computer and the large VAM but I will have to recheck the injectors and the wiring, when it gets a little warmer out. Some of the codes that I pulled off were talking about the BARO sensor and the MAP sensor. I don't know if these would be the same on both cars but I am using the MAP sensor for the 91 2.3 mustang and I don't know where the BARO sensor would be to see which one I am using.
Check your TPS.
To set the TPS you will need the following tools.
1. Small Phillips screwdriver
2. Digital Voltmeter
3. Analog Voltmeter
The base idle needs to be set properly prior to setting the TPS. see below for instructions on setting base idle
The next thing to do is hook up the analog meter to the green and Black wires. With the key on open and close the throttle body slowly, you should see the needle move in a smooth arc without jumping around. If the needle jumps there is a dead spot in the TPS and it will need to be replaced.
The next step is to set the TPS to the proper voltage with the key in the on position. Using your digital meter, connect to the same wires as you did in the above. The TPS voltage should be as close to .90V with the TB in the closed position. At full open (WOT) should be around 4.5V to 4.75 V. If the TPS is not within the above settings, loosen the 2 phillips head screws and rotate the TPS until you get to .90V at closed throttle. Tighten the screws, and recheck your settings again.
Next, what is your fuel pressure during boost? It should rise 1 psi for every psi of boost. Your fuel pressure at idle should be 40 with the vacuum hose disconnected, and 36-37 connected. Low or insufficient fuel pressure will cause the car to buck.
2.3 turbo bogs down and lacks power 
