Stalling 93 suburban

Hello everyone! I am new to this site, but I am in love!! Lots of great info. I recently bought a 93 suburban 4x4 with the 5.7ltr tbi system. It was running like crap when i bought it. I have done a lot of work to it but it still goes dead when I put a load on the motor (putting in gear or turning on a/c). I have changed the IAC, MAP, TPS. I have also put in new plugs,wires, distr. cap and rotor and pick-up coil. I have changed the fuel pump and filter. Also changed the fuel pressure regulator and the filters on the injectors. I checked for vac. leaks and could not find any. I took the throttle body off and gave a good cleaning and replaced the gasket just in case it was leaking. The only code i get is for the MAP sensor and I have changed it. I also took off the EGR and cleaned it. It seems to be working correctly. After all this I took it to my mech. and he could not find the problem either. I am wondering if it could be my ECM or maybe a bad fuel pump (even though it is a new one!). I would apprecate any help!!

Welcome to AF, checked vacuum to the map?, are both injectors spraying? Was the tank screen changed when the pump was done, is the fuel pressure ok under load?

I did check the vac lines to the MAP and also changed the tank screen when I changed the fuel pump. Both injectors seem to be spraying fine. I have not checked the fuel pressure yet cause I will have to go by a fuel pressure tester. I figured I would try something else since the fuel pump is new, but I am running out of options. I might go buy one this evening and check it.

Thanks!

You stated a large issue here, try something, it seems random parts are the plan of the day , I am not lecturing you but you have no idea what the source is, blocked cat, low pressure are what could cause the symptoms. A scan should be done to look at sensor inputs and fuel trims also, it is as you know, expensive to proceed in this way. Focus on map readings if you get a code , which could be high or low voltage based on what the ecm sees as percieved engine load/ throttle opening. Sounds like the engine is too lean,, hard to tell from here, that's where a comprehensive scan will help to eliminate guess work.

That is very true. It does get expensive to just go changing parts. I did take it to a mech. that said he did do a scan on the vehicle and said it did not tell him anything except a bad map sensor and that has been changed.

You need to find another mechanic, he in effect is saying he can't fix it, right?

EXACTLY!!! I have used this guy a couple of times and he has always done good work, but maybe I caught him on a bad day. I am asking around to try to find a good mech. in the area. I unpluged the wire for the timing and it seemed to idle better and stays running sometimes when put in gear. I am thinking that the timing may be off or it is retarding the timing too much. What do you think?

Thanks for all the help!!!