To preface, I got a pretty beat up fiero (86 Duke) a couple months back and the engine was just rebuilt. However it's had a couple of issues but the most notable is a loss of acceleration which causes the car to almost drag(?) the service eng. light also turns on due to it... However it turns off after a while. I've read the possibility of a bad TPS but I'm almost entirely new to working on my car, as well as the forum and would greatly appreciate any feedback.

Read this page and it may help you with your issue and any future issues. You need to see what code is being generated.
https://www.fiero.nl/cgi-bin/main.cgi?ECMCodes

Here is a picture from the internet showing location behind the cigarette lighter plate and the jumper installed.

[This message has been edited by IMSA GT (edited 01-12-2023).]

Many times light comes on then off. How fast depends how bad the problem that ECM sees.
Only a few things keep the light on all the time.

Use a small clip etc.
You need to jump as said above but do not use force a big wire in and damage the plug or when use a scan tool that won't connect in a wreck plug.

Warning: Even if has a "Code" often does not mean X sensor is bad.
Example: 44 or 45 can be several problems and not a "dead" O2 sensor.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Thank you both! I really appreciate it. The codes are news to me, I wondered how they were scanned. Will keep posted

W/ a scanner that works w/ GM version of "OBD1" ECMs/PCMs.

Example: https://reddevilriver.com/aldl.html

See my Cave, Scan Tool Help and other pages in same section.

Following up, I got back code 33 on two occasions. Before and after replacing the MAP sensor. Looking throughout other threads I read the possibility of a vacuum leak, if that is the case, is there any common leaks that happen in 2.5s?

Yeah pretty much every vacuum line should be inspected. EGR could leak. Could be low fuel pressure. God only knows.

I just finally solved a similar problem with my daughter's 86 2.5- the car would intermittently lose power while driving and every so often, simply not start. Turns out the TPS was possessed would periodically send the full 5v reference voltage to the ECM causing a severely rich mixture that would either bog down the car when driving or flood it when starting. Because TPS worked MOST of the time (including every time I tested it) it avoided suspicion.