OBD1 jumper question

[Gremcat]

When setting my timing a few weeks ago I jumped the terminals and saw the CEL flash once real quick but then stay out. Is that normal or do they normally flash a constant strobe etc?I am trying to trouble shoot a weird idle low top end issue. I already replaced the TPS and about everything in the exhaust and fuel system except the exhaust manifold. This coming week I am going to do the timing belt and tensioners, water pump, and thermostat. It has an erratic idle and when I go in neutral ( manual tranny ) it sometimes idles up to 2K and stays there. Then erratic idle again. It is also getting about 14.8 MPG with a 2" lift and 31" tires on the Hwy. I know these aren't real fuel efficient but I have heard of some folks running 33's and stock gears getting 17-19 mpg on the highway. Anyway just curious on the CEL. I asked a parts store to check for codes but they don't have the right diagnostic tool I guess. I thought maybe the 02 as well would help but hate to keep throwing parts at it. The MPG may be due to the fact that I am commuting 400 miles each way and have to keep it mid throttle to floored most of the time to keep it over 70.

 

[Gremcat]

List of parts swapped: Injectors, Fuel Pump, Filter, Tank, TPS, gaskets ( need to do again because my "mechanic" pulled the intake a second time and reused the gasket and the TB gasket was falling apart but stuck on so I didn't replace it but now realize that was a mistake), all new brakes and components, all new suspension, all new steering components, Flowmaster hi flow cat and exhaust. It's been an expensive few weeks. Going to do the timing belt etc. and replace the intake gaskets, all remaining coolant/vacuum lines. I also checked the EGR and it appears to be closing and opening properly. I will clean the backside of the throttle body and the intake when I do the gaskets. I did do the front side of the TB when I did the TPS. I have read of the TB wearing out but not sure how to check that or how it would even wear out?

 

[91'4bee]

Start with those gaskets. Bad idle is probably un-metered air. Also just try and get the codes. Jump those same terminals you did when doing the timing with the key on (engine not running) and see what flashes out.

Besides I only get 16 mpg right now...something about winter cause in the summer I get great gas mileage 18-20. But that cold air hits...its weird.

Good luck