1989 Ford Bronco Engine runs like S***

Not to butt in, but I would do a leak down test and check for vacuum leaks with a spray bottle of water. Go around the intake and the upper plenum and throttle body and egr vavle. I had an 89 F-150 and now a 95 F-150 and the both had a leaking egr vavle. I would also check the knock sensor if it is retarding the timing it also will not run good. To test the knock sensor simply hook up a timing light and tap the engine block (lightly) with a hammer near the sensor and see if the timing will retard. Hope this is helpful.

Ok great it is better but still check the knock sensor when you get a timing light in hand ok. A leak down test is putting air into the cylinder with both valves closed. What this tells us is a lot actually. This is something the engine shop should have asked the mechanic to do. What you do is put air to the cylinder like I said when both valves are closed and then you remove the oil cap and see if there is air coming out if so a ring or rings are bad if no air comes out then rings are fine. Then you listen at the exhaust pipe if air come out the exhaust bad valve if no air all it good. Now open the throttle and listen for air, if air come out bad intake valve if no air then it is good. You do this for each cylinder.

Surging usually means an intake manifold leak, either under the throttle body, or the intake itself. Using propane tool hunt for the leak, then when engine smoothes out, you have found it. EGR opening at the wrong time can be a problem too, check the EGR solenoid, it's got vac and an electrical connector on it, called EVR.