Throttle response

[bsmith]

hey guys my throttle on my 1987 gmc jimmy with tbi has been really random as far as throttle response is really random one minute its very responsive and quick to get up to speed and another minute its very laggy and slow to get up to speed

 

[1987 GMC Jimmy]

hey guys my throttle on my 1987 gmc jimmy with tbi has been really random as far as throttle response is really random one minute its very responsive and quick to get up to speed and another minute its very laggy and slow to get up to speed

I would say look at the TPS sensor, and maybe look at your timing also. Have you had any trouble codes, and do you know the paperclip method of pulling those codes? I'm going to attach a TPS sensor test procedure write up. Disregard the OBD2 trouble codes. The voltage range should be a smooth change from about .5V to about 4.5V at WOT. Also check your ground strap between the passenger side cylinder head and the firewall because that'll affect the TPS sensor. Your timing may be worth looking at at. I'd try 8* BTDC for your base timing and make sure your single wire EST bypass is disconnected at the driver side firewall when you adjust timing and that you disconnect the battery for thirty seconds after you're done. If nothing with this, I'd borrow a fuel pressure test kit from Autozone and see what you get. It should be about 13 PSI on a stock motor. That would be looking into a potentially failing fuel pump, but I'd try the easier ground strap, TPS, and timing first.

http://easyautodiagnostics.com/gm/4.3L-5.0L-5.7L/tp-sensor-tests-1