Here we go again.

Runs great when cold. Once it warms up, the idle alternates between smooth and rough. It'll run smooth for 30 seconds or so, then rough for another 30 or so, then smooth, then rough...You get the idea. Seems like an air control issue to me.

What have I done over the last month? 1. Moved the ignition control module (TFI) off the distributor and mounted it remotely, 2. replaced the ignition air control, 3. cleaned the EGR valve, 4. replaced the tps, 5. replaced the rotor and cap with an MSD cap and rotor, 6. replaced the coil with an MSD EFI coil, 7. cleaned the throttle body housing, 8. replaced the spark plug wires, 9. turned the throttle adjustment screw even though it's a no, no, 10. set timing 11. 3 months ago I replaced the lower intake manifold gaskets since it was leaking oil, 12. replaced accelerator cable as old one was damaged. 13. Oh yeah, I replaced the fuel filter too.

That about covers it. Anyway, I've got this problem when the engine is hot. When its cold, I'd win the Daytona! When its hot, it alternates between a good and rough idle. When on the road it runs ok, but I can feel it pick up speed a bit without giving it more fuel. All of a sudden, when cruising at 40 mph for an example it'll suddenly feel like it's running as it should and the vehicle will accelerate a few mph. I think it's an air problem. Any other opinions out there are appreciated. I want to fix this damn thing!!!

 

If you have a TFI module, that means you have a computer-controlled engine.

First step in diagnosing such is to ask the computer what's going on (pull codes).

Fuel Injection Technical Library » How To Run a Self-Test

 

You always recommend that, but I don't have the device whereby I can do that.

 

Well, yes, I always recommend that, as anything else is just shooting in the dark IMO. If you keep replacing enough parts you'll eventually come across the one needing attention but that's a pretty juvenile way of fixing something if you ask me.

If you know how to count, you can use a test light or analog volt meter to count blinks or needle sweeps (instructions in that link above or elsewhere on the 'net, Google on OBD-1 diagnostics or maybe KOEO KOER or some such). WalMart or Harbor Failure may have analog volt meters and maybe test lights, too.

If you don't have one, then purchase one, they're not expensive. You need to invest a certain amount in tools and diagnostic equipment if you're gonna own & maintain a ~30 yo vehicle.

If you don't live in California, you can take the vehicle to an auto parts store and borrow a code reader (but, be warned, many such employees don't know Thing One about pulling codes on an OBD-1 system, read up on that ahead of time and maybe you can teach them something.